JPH0684128A - Magnetic head - Google Patents

Abstract

PURPOSE:To obtain a magnetic head which enables high density recording and generates high reproducing outputs. CONSTITUTION:Ferromagnetic metallic thin films 3, 4 as a second magnetic body are arranged at the face where magnetic cores 1, 2 of oxide magnetic bodies butt against each other, thereby to constitute magnetic core half bodies 11, 12. The butting width of the metallic thin films 3, 4 is regulated by regulating notches 1b, 2b. The magnetic bodies butt each other also at the outside of the regulating notches 1b, 2b. Both end parts of a sliding face are processed to be rails along the sliding direction of a magnetic recording medium, and therefore the touching width to the magnetic recording medium is regulated. The butting width of the ferromagnetic metallic thin films 3, 4, namely, the track width Tw is set to be smaller than 25mum, and the butting width A of the magnetic bodies at the outside of the regulating notches is respectively not larger than 50mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called metal-in-gap type magnetic head in which the vicinity of a magnetic gap is made of a soft magnetic metal thin film.

[0002]

2. Description of the Related Art In the field of magnetic recording, high-density recording and short-wavelength recording have been studied due to demands for downsizing equipment such as video tape recorders (VTRs) and long-time recording. In response to the above, in magnetic recording media, high coercive force and high residual magnetic flux density, which are found in so-called metal tapes and vapor deposition tapes, are being advanced. Accordingly, the magnetic head is naturally required to have improved performance.

Under such circumstances, a so-called metal-in-gap type magnetic film is used in which a soft magnetic metal thin film having a high saturation magnetic flux density is arranged in the magnetic core, and the abutting portion of these soft magnetic metal thin films is used as an operating gap. The head was developed,
In particular, the magnetic head having the structure shown in FIG.
The application is being considered as suitable for a recording / reproducing apparatus for performing high density recording such as.

That is, the above-mentioned magnetic head comprises a pair of magnetic core halves 101 and 102 made of an oxide magnetic material. Thin film forming grooves 101a, 10 forming slopes on the abutting surfaces of the pair of magnetic core halves 101, 102.
2a is grooved. The thin film forming grooves 101a, 1
Ferromagnetic metal thin films 103 and 104 are arranged on 02a,
A magnetic gap g is formed by abutting one end faces of these ferromagnetic metal thin films with each other. The width of the abutting surfaces where the ferromagnetic metal thin films 103 and 104 abut each other is set to a predetermined track width Tw by the track width regulating grooves 101b and 102b formed along the thin film forming grooves 101a and 102a. Further, in the above magnetic head, the thin film forming groove 1 serving as the sliding surface of the magnetic recording medium is formed.
Both end portions of the surface orthogonal to 01a and 102a are rail-formed along the sliding direction to form a magnetic recording medium contact surface 105 having a predetermined contact width.

[0005]

By the way, in order to improve the recording density in a VTR or the like, it is necessary to narrow the track width and increase the number of recording tracks per unit area of the magnetic recording medium. In particular, in order to achieve the recording density required in recent years, the recording track width of the magnetic head must be suppressed to at least less than 25 μm.

However, in the magnetic head having the above structure, if the track width is to be suppressed to less than 25 μm, the abutting area of the ferromagnetic metal thin film will be narrowed.
As a result, the magnetic resistance of the magnetic path increases and the reproduction output falls below the practical level.

Therefore, the present invention has been proposed in view of such a conventional situation, and an object thereof is to provide a magnetic head capable of obtaining a sufficient reproduction output even when the track width is less than 25 μm. .

[0008]

In order to achieve the above object, in the magnetic head of the present invention, a ferromagnetic metal thin film is arranged as a second magnetic body on the abutting surface of a magnetic core made of an oxide magnetic body. To form a magnetic core half body, the abutting width of the ferromagnetic metal thin film is regulated by the track width regulating groove, and the magnetic body is abutted on the outer side of the track width regulating groove. In a magnetic head in which both end portions of rails are railed along the sliding direction of the magnetic recording medium and the contact width against the magnetic recording medium is regulated, the abutting width regulated by the track width regulating groove of the ferromagnetic metal thin film is less than 25 μm. The abutting width of the magnetic material in the outer portion of the track width regulating groove is 50 μm or less.

The thickness of the magnetic core half on the back side is 150 to 200 μm. Further, the abutting width of the magnetic material in the outer portion of the track width regulating groove is 10 to 50 μm.

[0010]

A ferromagnetic metal thin film is arranged as a second magnetic body on each abutting surface of a magnetic core made of an oxide magnetic material to form a magnetic core half body, and the abutting width of the ferromagnetic metal thin film is regulated by a track width. It is regulated by the groove, and magnetic bodies are abutted on the outer side of the track width regulating groove, and both end portions of the sliding surface are rail-machined along the sliding direction of the magnetic recording medium, and the contact width against the magnetic recording medium is obtained. In the magnetic head in which the magnetic field is restricted, if the abutting width of the magnetic material in the outer portion of the track width restriction groove is optimized, the magnetic resistance of the magnetic path is adjusted and a high reproduction output is obtained. Further, if the head thickness on the back side is further optimized, the inductance is adjusted, and the effective reproduction output E / √L (E: reproduction output, L: inductance) is improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic head to which the present invention is applied will be described below with reference to the drawings.

The magnetic head of the present embodiment is a magnetic head in which ferromagnetic metal thin films are obliquely connected on the contact surface of the magnetic recording medium. As shown in FIGS.
Reference numeral 12 is mainly composed of core parts 1 and 2 made of an oxide magnetic material such as Mn-Zn ferrite, and ferromagnetic metal thin films 3 and 4 are arranged at the abutting parts.

On the abutting surfaces of the core portions 1 and 2, thin film forming grooves 1a and 2a are formed so as to form inclined surfaces which are oblique when viewed on the side facing the magnetic recording medium. Ferromagnetic metal thin films 3 and 4 are formed on the grooves 1a and 2a. Then, the magnetic core halves 11 and 12 are arranged so that one end faces of the ferromagnetic metal thin films 3 and 4 are butted against each other.
Are joined together via a gap material to form a closed magnetic circuit, and a magnetic gap g is formed at the abutting surface E _G of the ferromagnetic metal thin films 3 and 4.

Track width regulating grooves 1b and 2b are formed in the core portions 1 and 2 along the thin film forming grooves 1a and 2a, whereby the ferromagnetic metal thin films 3 and 3 are formed.
The width of the abutting surface E _G of No. 4 is a predetermined track width Tw. In this magnetic head, since the magnetic bodies abut on the outer side portions of the track width regulating grooves 1b and 2b, the abutting surfaces E _G of the ferromagnetic metal thin films 3 and 4 and the magnetic body abutting surface E on the outer side portions thereof. _A also secures the magnetic path.

One of the magnetic core halves 11, 12 is provided with a winding groove 7 for winding a coil, so that the depth of the magnetic gap g can be reduced. At the same time as the determination, by winding a coil through the winding groove 7, a recording signal is supplied to the magnetic head by electromagnetic induction or a reproduction signal is taken out.

Also, the joined magnetic core halves 11, 12
Is a magnetic recording medium contact surface 8 having a predetermined contact width by railing both end portions of a surface orthogonal to the thin film forming grooves 1a and 2a which are magnetic recording medium sliding surfaces along the sliding direction.
Therefore, an edge portion parallel to the magnetic gap g prevents an extra signal from being picked up.

In the magnetic head having such a structure, the ferromagnetic metal thin films 3 and 4 are thin film forming grooves 1 forming slopes.
Since the films are formed on a and 2a, they are obliquely connected to each other with the magnetic gap g sandwiched therebetween, and the interfaces between the core parts 1 and 2 made of an oxide magnetic material and the soft magnetic metal thin films 3 and 4 due to so-called azimuth loss. Does not operate as a pseudo gap with respect to the magnetic gap g.

Here, the inclination angle of the slopes of the thin film forming grooves 1a, 2a (that is, the ferromagnetic metal thin films 3, 4) with respect to the magnetic gap is preferably set in the range of about 20 ° to 80 °. If this inclination angle is 20 ° or less, crosstalk from adjacent tracks becomes large. The inclination angle is preferably 30 ° or more. On the other hand, when the inclination angle exceeds 80 °, it is necessary to form the ferromagnetic metal thin film, which will be described later, in the vicinity of the magnetic gap to have the same film thickness as the track width, and the thin film is formed using the vacuum thin film forming technique. It takes a lot of time,
It is not preferable because the film structure becomes non-uniform.

Further, the widths of the thin film forming grooves 1a and 2a and the track width regulating grooves 1b and 2b are required to be 40 μm or more from the viewpoint of grindstone processing accuracy in the manufacturing process and grindstone wearability. If the width is too large, for example, when the glass is filled in the groove as a non-magnetic material, the head has cracks because the glass has a different thermal expansion coefficient from the magnetic core made of an oxide magnetic material or the ferromagnetic metal thin film. . Therefore, these grooves 1a, 2a, 1
The width of b and 2b is preferably 40 to 140 μm or less.

In order to enable high density recording in the magnetic head having such a structure, the track width T is set.
It is necessary to set w to less than 25 μm, but if the track width is less than 25 μm, the area of the abutting surface E _G of the ferromagnetic metal thin film becomes small, the magnetic resistance of the magnetic path increases, and the reproduction output decreases.

Therefore, in the present invention, the magnetic resistance of the magnetic path is adjusted by optimizing the width A of the abutting surface E _A of the magnetic material in the outer portion of the track width regulating groove that is not related to the track width, thereby achieving high density recording and high recording. Both of the playback outputs will be achieved. Furthermore, the effective playback output is represented by E / √L,
It depends on the inductance as well as the magnetic resistance. Therefore, the abutting surface E _A of the magnetic body in the outer portion is
The width A is optimized for each head thickness on the back side, the inductance is adjusted together with the magnetic resistance, and the effective reproduction output is improved. The appropriate value of the width A will be illustrated below for the magnetic heads having a head thickness of 200 μm, 130 μm, and 300 μm on the back side.

That is, FIGS. 3 to 5 show the relationship between the width A of the abutting surface E _A of the magnetic material in the outer portion and the reproduction output E / √L per inductance L. Where E / √
L is a relative value, and therefore the characteristic curves in each figure show only the changing tendency of E / √L. Further, FIGS. 3, 4 and 5 respectively show a magnetic head having a head thickness of 200 μm on the back side and an abutting surface E of the outer portion when the width A of the abutting surface E _A of the magnetic body in the outer portion is 0 μm.
_When the width A of A is 0 μm, the head thickness on the back side is 1
The magnetic head has a thickness of 30 μm, and the width A of the abutting surface E _A of the magnetic material in the outer portion is 0 μm, and the head thickness on the back side is 300 μm.

First, the head thickness on the back side shown in FIG.
Looking at the characteristic curve of the magnetic head of 00 μm, when the track width is less than 25 μm, E / √L is such that the width A of the abutting surface E _A of the magnetic material of the outer part is 0 to 10 μm.
And the width A maintains a substantially constant value in the range of 10 to 50 μm. When the width A exceeds 50 μm, the width A decreases as the width A increases, and the practical E / √L value is not exhibited. Therefore, the back side head thickness is 20
With a magnetic head of 0 μm and a track width of less than 25 μm,
The width A of the abutting surface E _A of the magnetic material in the outer portion is set to 1
It is set to 0 to 50 μm.

It should be noted that E / √L shows an inverse change of increase / decrease depending on the width A of the abutting surface E _A of the magnetic body in the outer portion, but the increase of E / √L due to the increase of the width A causes the increase in the magnetic path. This is because the magnetic resistance decreases, and the decrease in E / √L due to the increase in width A is due to the increase in the volume and the increase in inductance of the magnetic head itself.

Incidentally, when the track width is 25 μm, E / √L continues to decrease as the width A of the abutting surface E _A of the magnetic material in the outer portion increases. When the track width is relatively large at 25 μm, the magnetic resistance is sufficiently low only by the high-permeability ferromagnetic metal thin film forming the magnetic gap.
/ √L does not become larger than that. When the width A is increased, on the contrary, the volume of the magnetic head itself is increased, so that the inductance is increased and E / √L is decreased.

Next, the back side head thickness shown in FIG. 4 is 1
Looking at the characteristic curve of the magnetic head of 30 μm, E / √L is the abutting surface E when the track width is less than 25 μm.
_When the width A of A is 0 to 20 μm, it keeps a substantially constant value,
When the width A exceeds 20 μm, the width A decreases as the width A increases, and when it exceeds 50 μm, a practical E / √L value is not exhibited. Therefore, in a magnetic head having a head thickness of 130 μm and a track width of less than 25 μm, the width A of the abutting surface E _A of the magnetic body in the outer portion is set to 50 μm or less.

Further, looking at the characteristic curve of the magnetic head having a head thickness of 300 μm on the back side shown in FIG. 5, E / √L is the abutting surface E _A of the magnetic material in the outer portion when the track width is less than 25 μm. The width A decreases as the width A increases, and when it exceeds 50 μm, a practical E / √L value is not exhibited. Therefore, in a magnetic head having a head thickness of 130 μm and a track width of less than 25 μm, the width A of the abutting surface E _A of the magnetic body in the outer portion is set to 50 μm or less.

When the absolute values of E / √L of the magnetic heads are compared, as shown in FIG. 6, the head thickness is 300 μm.
Of the head thickness is 200 μm and 130 μm, the absolute value of E / √L is 3 to 4 dB smaller. That is, the head thickness is preferably 150 to 200 μm.

The magnetic head having such a structure is manufactured as follows. First, a ferromagnetic oxide substrate whose surface is processed with good parallelism and smoothness by lapping or the like and is made of, for example, Mn—Zn ferrite is prepared. And
As shown in FIG. 7, a plurality of thin film forming grooves 22 each having an inclined surface 23 are formed in parallel with each other over the entire width on the upper surface 21a corresponding to the magnetic gap forming surface of the ferromagnetic oxide substrate 21 by a rotating grindstone process or the like.

Then, a ferromagnetic metal is deposited on the above-mentioned ferromagnetic oxide substrate 21 by a vacuum thin film forming technique.
The ferromagnetic metal thin film 2 is formed on the thin film forming groove 22 as shown in FIG.
5 is formed.

As the material of the ferromagnetic metal thin film 25,
Ferromagnetic amorphous metal alloy So-called amorphous alloy (for example, one or more elements of Fe, Ni, Co and P, C,
An alloy composed of one or more elements of B and Si, or Al, Ge, Be, Sn, In, Mo, W
Alloys containing Ti, Mn, Cr, Zr, Hf, Nb, etc.), Sendust alloys that are Fe-Al-Si based alloys,
Fe-Al alloys, Fe-Si alloys, permalloys, etc. can be used, and the film deposition method is represented by flash vapor deposition, vapor deposition in gas, ion plating, sputtering, cluster ion beam method and the like. Vacuum thin film forming technology is adopted.

Then, as shown in FIG. 9, a non-magnetic material 26 such as glass is filled in the thin film forming groove 22 covered with the ferromagnetic metal thin film 25 of the ferromagnetic oxide substrate 21.
The extra ferromagnetic metal thin film 25 on the upper surface 21a is removed by surface grinding.

Further, as shown in FIG. 10, a plurality of track width regulating grooves 27 are formed adjacent to the slope 23 on which the ferromagnetic metal thin film 25 is adhered and parallel to the thin film forming groove 22.
At this time, the position of the track width regulating groove 27 is set to this groove 27.
Is set so as to substantially coincide with the end of the ferromagnetic metal thin film 25 formed on the slope 23. Then top surface 2
1a is flat-polished and further mirror-finished to correct the track width Tw, and the thin film forming groove 22 and the track width regulating groove 2 are formed on the upper surface 21a, that is, the magnetic gap forming surface.
The core block 35 is formed so that the ferromagnetic metal thin film 25 whose track width is regulated by 7 faces.

Through the above steps, two core blocks 35 shown in FIG. 10 are manufactured. Then, for one of the pair of core blocks 35, 35, as shown in FIG. 11, a winding groove 31 and a glass groove 32 which are orthogonal to the thin film forming groove 22 and the track width regulating groove 27.
Are formed in parallel to form the core block 36.

Next, the upper surface 35a which becomes the magnetic gap forming surface of the core block 35 shown in FIG. 10 and the upper surface which becomes the magnetic gap forming surface of the core block 36 in which the winding groove 31 and the glass groove are provided as shown in FIG. As shown in FIG. 12, the ferromagnetic metal thin films 15, 15 facing the respective magnetic gap forming surfaces are aligned with each other via a gap spacer filmed on one of the upper surfaces 35a, 36a. Overlaid on. Then, the non-magnetic material 33 such as glass is melted from the winding groove 31 and the glass groove 32 to fuse the pair of core blocks 35 and 36, and the non-magnetic material 33 is filled in each track width regulating groove 27. In addition,
As the gap spacer, SiO ₂ , ZrO ₂ ,
Ta ₂ O ₃ , Cr or the like can be used.

Finally, the core block 3 is made by glass fusion.
The magnetic heads 5 and 36 are integrated and cut into a magnetic head.
First, the vicinity of the glass groove 32 provided for fusing glass on the back gap side is cut and removed. Then, the positions of the end of the contact surface of the magnetic recording medium and the end of the magnetic head (that is, the position where the width A of the abutting surface E _A of the outer portion has a predetermined value) are regulated, and based on these regulated positions. As shown in FIG. 13, a butt surface forming groove 37 on the outer side is formed. Then, a in the abutting surface forming groove 37 of the outer portion
After a plurality of head chips are cut by slicing at the positions of the -a line and the a'-a 'line, the magnetic recording medium contact surface is cylindrically polished to manufacture a magnetic head as shown in FIG. .

[0037]

As is apparent from the above description, in the present invention, a ferromagnetic metal thin film is arranged as a second magnetic body on each of the abutting surfaces of a magnetic core made of an oxide magnetic body to form a magnetic core half. The track width regulation groove regulates the abutting width of the ferromagnetic metal thin film, and the magnetic bodies abut against each other on the outer side of the track width regulation groove. In a magnetic head in which a rail is machined along the sliding direction of the recording medium and the contact width against the magnetic recording medium is restricted,
Since the abutting width of the oxide magnetic material and the ferromagnetic metal thin film on the outer side of the track width regulating groove is 50 μm or less, a high reproduction output can be obtained even when the track width is less than 25 μm.

Therefore, according to the present invention, it is possible to increase the number of recording tracks per unit area of the magnetic recording medium in a VTR or the like, and high density recording is achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a magnetic head of the present invention.

FIG. 2 is a plan view of the magnetic head as viewed from the contact surface side of the magnetic recording medium.

Head thickness of the back side showing the reproduction output E / √L relationships width A and per inductance L of the abutment surface E _A of the magnetic head of 130μm when the width A of FIG. 3 abutting faces E _A is 0μm It is a characteristic diagram.

Head thickness of the back side showing the reproduction output E / √L relationships width A and per inductance L of the abutment surface E _A at 200μm magnetic head when the width A of FIG. 4 abutting surfaces E _A is 0μm It is a characteristic diagram.

Head thickness of the back side showing the reproduction output E / √L relationships width A and per inductance L of the abutment surface E _A at 300μm magnetic head when [5] the width A of the abutting surface E _A is 0μm It is a characteristic diagram.

FIG. 6 is a characteristic diagram showing absolute values of E / √L of magnetic heads having various head thicknesses.

FIG. 7 is a perspective view showing a thin film formation groove forming step.

FIG. 8 is a perspective view showing a ferromagnetic metal thin film forming step.

FIG. 9 is a perspective view showing a non-magnetic material filling step.

FIG. 10 is a perspective view showing a track width regulating groove forming step.

FIG. 11 is a perspective view showing a winding groove and glass groove forming step.

FIG. 12 is a perspective view showing a core block joining step.

FIG. 13 is a perspective view showing a magnetic recording medium facing surface forming step.

FIG. 14 is a perspective view showing a manufactured magnetic head.

FIG. 15 is a plan view of a conventional magnetic head as viewed from the contact surface side of a magnetic recording medium.

[Explanation of symbols]

 11, 12 ... Magnetic core halves 1, 2 ... Core portions 1a, 2a ... Thin film forming groove 1b. 2b ... Track width regulating groove 3,4 ... ferromagnetic metal thin film 8 ... magnetic recording medium contact surface

Claims (3)

[Claims] 1. A magnetic core half body is constructed by disposing a ferromagnetic metal thin film as a second magnetic body on each of the abutting surfaces of a magnetic core made of an oxide magnetic material, and the abutting width of the ferromagnetic metal thin film is a track. The magnetic recording medium is regulated by the width regulation groove, and the magnetic material is abutted on the outer side portion of the track width regulation groove, and both ends of the sliding surface are rail-machined along the sliding direction of the magnetic recording medium. In the magnetic head having a restricted contact width, the abutting width of the ferromagnetic metal thin film regulated by the track width regulating groove is less than 25 μm, and the abutting width of the magnetic material in the outer portion of the track width regulating groove is 5 μm.
A magnetic head having a thickness of 0 μm or less. 2. The magnetic head according to claim 1, wherein the thickness of the magnetic core half on the back side is 150 to 200 μm. 3. The magnetic head according to claim 2, wherein the abutting width of the magnetic material on the outer side portion of the track width regulating groove is 10 to 50 μm.