JPH0729117A - Magnetic head - Google Patents

Abstract

PURPOSE:To obtain a magnetic head which has a large saturated magnetic field and superior recording efficiency. CONSTITUTION:In the magnetic head, end faces of ferromagnetic metallic thin films are butted each other thereby to form a magnetic gap therebetween. The ferromagnetic metallic thin films are formed at surfaces 1a, 2a of a metallic magnetic thin film which are obtained by notching slantwise butting surfaces of a pair of half bodies 1 and 2 of a magnetic core. The thickness (t) of the ferromagnetic metallic thin film measured in the vertical direction from the surfaces 1a and 2a is set to be larger than a bonding length L in the vicinity of the magnetic gap. The bonding length L of the magnetic gap is 15mum or smaller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head, in particular, a pair of core halves each having a ferromagnetic metal thin film formed on the abutting surfaces of the core halves, and the end faces of the ferromagnetic metal thin films of both core halves are butted against each other. The present invention relates to a narrow track magnetic head in which an operating magnetic gap is formed between both end surfaces.

[0002]

2. Description of the Related Art In recent years, in a magnetic recording / reproducing apparatus such as a VTR, a so-called metal tape using ferromagnetic metal powder or a non-magnetic support is directly coated with a ferromagnetic metal material in order to improve image quality. Magnetic recording media having a high coercive force such as the above vapor deposition tape are being used. Since this type of magnetic recording medium has a high coercive force Hc, a high saturation magnetic flux density Bs is also required for the material of the magnetic head for recording and reproducing.

Therefore, the applicant of the present invention previously disclosed in Japanese Patent Laid-Open No. 60-2.
In Japanese Patent No. 29210, a magnetic head suitable for high-density recording / reproducing on a magnetic recording medium having a high coercive force such as a metal tape was proposed.

This magnetic head has a metal-in-gap type structure, for example, as shown in FIG. 15 which is an enlarged perspective view thereof and FIG. 16 is an enlarged front view of a part thereof. That is, the pair of magnetic core halves 101 and 102 are formed of a ferromagnetic oxide having a high magnetic permeability, and the joining surface of the magnetic core halves 101 and 102 is obliquely cut to form a ferromagnetic metal thin film forming surface 101a. On the surface 102a, a ferromagnetic metal thin film 103 having a high saturation magnetic flux density Bs is continuously formed to a thickness of t from the front gap forming surface to the back gap forming surface.

Then, the pair of magnetic core halves 10
1, 102 are abutted against each other via a gap material, and the contact surface of the ferromagnetic metal thin film 103 is configured to have a magnetic gap g having a gap junction length L and a track width Tw. Further, on the abutting surfaces of the magnetic core halves 101 and 102, winding grooves 106 and 1 for restricting the depth of the magnetic gap g and winding the coil 108.
07 are formed.

Here, each of the magnetic core halves 101, 10
The ferromagnetic metal thin film 103 formed on the second magnetic tape 103 is aligned in a straight line when viewed from the magnetic tape contact surface, and is at an angle θ with respect to the abutting surface 110 of the magnetic core halves 101 and 102. It is inclined.

A second kerf 101b for controlling the track width is formed on the joint surface of the magnetic core halves 101, 102.
102b is provided to secure a distance between the ferromagnetic oxide that faces the grooves 101b and 102b and the ferromagnetic metal thin film 103 that faces the groove, and the symmetrical balance of the groove prevents stress on the ferromagnetic oxide during processing. It is made small to prevent the generation of microcracks in the magnetic core halves 101, 102.

In the vicinity of the surface where the magnetic gap g is formed,
That is, on both sides of the magnetic gap g on the magnetic tape contacting surface, the track width is regulated and the ferromagnetic metal thin film 10 is formed.
The non-magnetic materials 104 and 105 for preventing the wear of No. 3 are melt-filled.

A method of manufacturing a narrow track magnetic head of this type is disclosed in, for example, Japanese Patent Laid-Open No. 61-
No. 105710.

[0010]

As described above, the material used for such a magnetic head has a high saturation magnetic flux density B.
Since s is required, a ferromagnetic metal thin film is used as a material for forming the magnetic gap g, and magnetic ferrite is used as a substrate for forming the ferromagnetic metal thin film. With such a material configuration, the total magnetic flux flowing from the ferromagnetic metal thin film and the magnetic ferrite at the time of recording the magnetic signal merges into the gap portion, so that a magnetic field in the gap equal to or higher than the saturation magnetic flux density Bs of the magnetic ferrite is obtained. Therefore, it becomes possible to record a magnetic signal even on a magnetic recording medium having a high coercive force.

In such a magnetic head, since the joint surface between the ferromagnetic metal thin films forms the magnetic gap g, the amount of magnetic flux that can pass through the joint surface between the ferromagnetic metal thin films is the leakage of the magnetic head. It will determine the strength of the magnetic field. However, the ferromagnetic metal thin film is
The thickness t of the ferromagnetic metal thin film measured in the vertical direction from the ferromagnetic metal thin film formation surface in the vicinity of the magnetic gap g is smaller than the gap junction length L because of the inclination angle. That is, since the magnetic path cross-sectional area of the ferromagnetic metal thin film is smaller than the area of the surface forming the magnetic gap g,
The saturation magnetic field is reached in the magnetic path before reaching the saturation magnetic field in the magnetic gap g.

In particular, in a magnetic head having a small gap junction length L, in other words, a small track width Tw, there is a problem that the above tendency becomes remarkable and the recording efficiency is lowered.

Therefore, the present invention has been proposed in view of the above conventional circumstances, and sufficiently exhibits the high saturation magnetic flux density Bs of the ferromagnetic metal thin film even in a magnetic head having a narrow track width. It is an object of the present invention to provide a magnetic head having a structure that can be formed.

[0014]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to achieve the above-mentioned object, in which a pair of core halves is provided with a groove having an inclined surface facing the abutting surfaces of the core halves. In a magnetic head in which the end faces of the ferromagnetic metal thin film formed on the slope are abutted against each other to form a magnetic gap g therebetween, the thickness t of the ferromagnetic metal thin film measured in the vertical direction from the slope is: It is larger than the gap junction length L in the vicinity of the magnetic gap g.

In the present invention, the gap junction length L is preferably 15 μm or less.

[0016]

When the thickness t of the ferromagnetic metal thin film is larger than the gap junction length L, the magnetic path cross-sectional area of the ferromagnetic metal thin film near the magnetic gap g is the surface forming the magnetic gap g (ferromagnetic metal thin film). Area of the butt surface) of the. Therefore, the saturation magnetic field does not reach the magnetic path before reaching the saturation magnetic field on the magnetic gap g formation surface. Therefore, a large leakage magnetic field can be generated in the magnetic gap g, and the recording efficiency of the magnetic head can be improved.

In particular, it is effective for improving the recording efficiency of a magnetic head having a small gap junction length L, in other words, a small track width Tw.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings.

First, a structural example of the magnetic head according to the present invention will be described. In this magnetic head, as shown in an enlarged perspective view of FIG. 1 and an enlarged front view of a part thereof in FIG. 2, a pair of magnetic core halves 1 and 2 are made of a ferromagnetic oxide such as a single crystal ferrite. The magnetic metal thin film forming surfaces 1a and 2a formed by obliquely cutting the joining surfaces of the magnetic core halves 1 and 2 are continuously formed from the front gap forming surface to the back gap forming surface by FeAlSi. A ferromagnetic metal thin film 3 having a high saturation magnetic flux density Bs of a system alloy (sendust) or the like is deposited to a thickness of t.

Then, the pair of magnetic core halves 1, 2
Are abutted against each other via a gap material such as SiO _{2 so} that the contact surface of the ferromagnetic metal thin film 3 becomes a magnetic gap g having a gap junction length L and a track width Tw. Moreover, winding grooves 6 and 7 for restricting the depth of the magnetic gap g and winding the coil 8 are formed on the abutting surfaces of the magnetic core halves 1 and 2.

The ferromagnetic metal thin films 3 formed on the magnetic core halves 1 and 2 are arranged in a substantially straight line when viewed from the magnetic tape sliding contact surface. The bodies 1 and 2 are inclined at an angle of θ with respect to the abutting surface 10.

The joint surfaces of the magnetic core halves 1 and 2 are provided with second kerfs 1b and 2b for controlling the track width. The second kerfs 1b and 2b are provided with the ferromagnetic metal thin film forming surfaces 1a and 2 on which the ferromagnetic metal thin film 3 is formed.
Since it is formed so as to slightly overlap one side edge of a, the thickness of the ferromagnetic metal thin film 3 is smaller than t in the vicinity of the abutting surface 10. Therefore, in the conventional magnetic head as shown in FIGS. 15 and 16, the gap junction length L was larger than t, while the magnetic head of the present invention had the gap junction length L smaller than t. It is possible.

The cut grooves 1b and 2b are formed so that the shape of the interface between the non-magnetic material 5 and the ferromagnetic oxide is bent. For example, when the magnetic head is viewed from the contact surface of the magnetic tape. In some cases, the cutting may be performed with a curved surface such that the shape of the interface is a substantially arc shape. Cut grooves 1b and 2b
By providing the groove, the distance between the ferromagnetic oxide facing the kerfs 1b and 2b and the ferromagnetic metal thin film 3 facing the kerf can be ensured, and the symmetrical balance of the grooves can reduce stress on the ferromagnetic oxide during processing. Can be made small, and the generation of microcracks in the magnetic core halves 1 and 2 can be prevented.

The grooves in which the ferromagnetic metal thin film 3 is formed and the kerfs 1b and 2b are filled with non-magnetic materials 4 and 5, respectively, so that the vicinity of the surface where the magnetic gap g is formed, that is, The track width Tw is regulated at both sides of the magnetic gap g on the contact surface of the magnetic tape, and the wear of the ferromagnetic metal thin film 3 is prevented.

On the other hand, the ferromagnetic metal thin film forming surfaces 1a, 2
The angle θ formed by a and the abutting surface 10 is 20 ° to 80 °
It is preferable to set within the range. This tilt angle θ is 2
If it is 0 ° or less, the crosstalk from the adjacent track becomes large. Further, when θ = 90 °, wear resistance is inferior, so it is preferable to set it to about 80 ° or less.
In this example, θ = 40 °.

Further, a method of manufacturing the above magnetic head will be described with reference to FIG.
~ It demonstrates with reference to FIG. First, the magnetic substrate 20 is prepared. In this embodiment, as the magnetic substrate 20,
Although single crystal ferrite was used, polycrystalline ferrite substrate,
A bonded substrate of single crystal ferrite and polycrystalline ferrite, a bonded substrate of single crystal substrates having different plane indices, or the like may be used. A non-magnetic substrate such as crystallized glass or non-magnetic oxide can also be used.

Then, as shown in FIG. 3, on the upper surface 20a of the magnetic substrate 20, that is, on the joint surface when the magnetic core halves are butted, a first kerf 21 having a substantially V-shaped cross section is entirely formed by a rotary grindstone or the like. A plurality of ferromagnetic metal thin film forming surfaces 21a are formed in parallel with each other. The ferromagnetic metal thin film forming surface 21a is formed as an inclined surface that is inclined at a predetermined angle θ with the upper surface 20a of the magnetic substrate 20 corresponding to the abutting surface of the magnetic cores, and the angle θ is 40 °. did.

Next, as shown in FIG. 4, the magnetic substrate 2
The ferromagnetic metal thin film 23 was formed by depositing on the entire surface of 0.
In this embodiment, the FeAlSi-based alloy (sendust) is deposited to a thickness of t, but a metal having a high magnetic permeability and a high saturation magnetic flux density, such as the above-mentioned sendust or O,
Thin film of alloy containing N, Ti, or FeRuGa
Si-based alloys, crystalline magnetic films containing O and N therein, Fe-based microcrystalline films, Co-based microcrystalline films, soft magnetic amorphous, and nitriding-based or carbonized soft-magnetic materials Metal thin films can be used, and these may be formed by a physical vapor deposition method, for example, a magnetron type sputtering method.

A ferromagnetic metal thin film 23 is formed on the magnetic substrate 20.
It is also effective to preliminarily form Cr or the like in order to prevent a chemical reaction between the magnetic substrate 20 and the ferromagnetic metal thin film 23 and to improve the adhesive force before forming the. Further, after the ferromagnetic metal thin film 23 is formed, Cr or SiO is used to prevent surface oxidation.
_You may form ₂ etc.

After forming the ferromagnetic metal thin film 23 as described above, as shown in FIG. 5, the non-magnetic material 24 is formed in the first kerf 21 on which the metal thin film 23 is formed. Then, the upper surface 20a of the magnetic substrate 20 is flat-polished to remove the excess metal thin film 23 on the upper surface 20a. Further, the surface of the magnetic substrate 2 is smoothed so that the magnetic substrate 2
An end surface of the ferromagnetic metal thin film 23 deposited on the ferromagnetic metal thin film forming surface 21a is exposed on the upper surface 20a of the No. 0.

Further, as shown in FIG. 6, the ferromagnetic metal thin film forming surface 21 on which the ferromagnetic metal thin film 23 is adhered and formed.
Adjacent to a, the second kerf 2 is provided so as to be slightly overlapped with one side edge of the first kerf 21 and parallel to the first kerf 21.
5, the upper surface 20a of the magnetic substrate 20 is mirror-finished. As a result, the ferromagnetic metal thin film 23
The magnetic gap g is constituted by only the
Will be regulated.

At this time, the second kerf 25 and the first kerf 2
1 overlapping amount, ie ferromagnetic metal thin film 2
It is possible to regulate the gap junction length L to a desired size by adjusting the cutout amount of No. 3 and further by chamfering the upper surface 20a of the magnetic substrate 20, but in the present invention, It was created so that L <t.

The groove shape of the second kerf 25 may be a simple V-shape, but may be, for example, polygonal or semicircular in cross section, and the inner wall surface of the kerf 25 may be formed in two steps or. By making the shape bent more than that, the distance between the ferromagnetic oxide and the ferromagnetic metal thin film can be secured to some extent. With such a groove shape, it is possible to reduce the crosstalk component due to the reproduction of the long-wavelength component signal, and further, the end faces of the track width regulating groove portions are inclined in the directions different from the azimuth angle of the magnetic gap. Thus, crosstalk from adjacent tracks or adjacent tracks is reduced.

Furthermore, the ferromagnetic metal thin film forming surface 2
Since the ferromagnetic metal thin film 23 is deposited on the la 1a and then the second kerf 25 for controlling the track width is formed, the cutting position of the second kerf 25 is changed. By adjusting it, the track width can be regulated with high accuracy, and a magnetic head with a shape that allows magnetic flux to pass through the ferromagnetic oxide through the shortest distance from the magnetic gap part composed of only a ferromagnetic metal thin film is manufactured with good yield. In addition to being able to do so, the output becomes large, which is advantageous in terms of productivity, reliability, and manufacturing cost.

Then, as shown in FIG. 7, the first kerf 21 and the second kerf 25 are formed on the magnetic substrate 20.
Grooves are formed in a direction orthogonal to, and a plurality of winding grooves 26 and an H groove 27 for inserting a glass rod at the time of joining are formed. Then, the core block 29 is cut out by cutting the magnetic substrate 20.

Subsequently, as shown in FIG. 8, a pair of core blocks 29 are opposed to each other, and they are arranged so that the ferromagnetic metal thin films 23 are abutted to each other via a gap spacer. Then, these core blocks 29 are fused by glass, and at the same time, the non-magnetic material 28 is filled in the second kerfs 25.

The gap spacer is S
iO ₂ , ZrO ₂ , Ta ₂ O ₅ , Cr or the like is used.
Further, in this manufacturing process, the filling of the non-magnetic material 28 into the second kerf 25 is not performed at the same time as the fusion of the core blocks 29, but in the step of FIG. Alternatively, the non-magnetic material 28 may be filled in and the glass fusion may be performed only in the step shown in FIG.

Then, after the magnetic tape sliding contact surface is cylindrically polished, slicing is performed at the positions of lines AA and A'-A 'in FIG. A magnetic head as shown in is completed. At this time, the slicing direction with respect to the joined core block 29 was inclined with respect to the abutting surface to form a magnetic head for azimuth recording.

In the magnetic head thus formed, the junction surface of the ferromagnetic metal thin film 3 and the ferromagnetic oxide, that is, the ferromagnetic metal thin film forming surface 1a or 2a, and the ferromagnetic metal thin film 3 are formed.
Since the pseudo gap formed by the joint surface between the nonmagnetic material 4 or 5 and the nonmagnetic material 4 or 5 is formed non-parallel to the gap surface of the operating magnetic gap g, the azimuth loss becomes large, and the substantial effect of this pseudo gap can be avoided. is there.

In the above embodiments, the core halves 1 and 2 are made of a magnetic material. However, when they are made of a non-magnetic material such as crystallized glass, potassium titanate, barium titanate, etc. In FIG. 1, the depths of the winding grooves 6 and 7 that regulate the gap depth are selected so as not to cross the ferromagnetic metal thin film 3, and the ferromagnetic metal thin film 3 extends to the back gap to set the operating magnetic gap g. It is indispensable to make it a closed magnetic circuit including.

Further, in the magnetic head shown in FIG. 1, the winding grooves 6 and 7 are formed in the opposite directions of the core halves 1 and 2, respectively, but only one of the winding grooves 6 and 7 is formed. The present invention can be applied to magnetic heads that are variously modified and modified, not limited to the above-described examples, such as a magnetic head having a configuration for forming 7.

Experiment 1 Here, the following experiment was conducted in order to compare the above-described magnetic head of the present invention with a conventional magnetic head.

First, in the magnetic head having the above structure, the gap junction length L is set to 10 μm, and the magnitude of the saturation magnetic field in the magnetic gap is simulated when the thickness t of the ferromagnetic metal thin film is variously changed. Calculated by Similarly, when L = 15 μm and L = 20 μm were set and the thickness t of the ferromagnetic metal thin film was variously changed, the magnitude of the saturation magnetic field in the vicinity of the magnetic gap g was calculated by simulation. The saturation magnetic flux density Bs of the ferromagnetic metal thin film was 1.0T.

In the magnetic head with L = 10 μm shown in FIG. 9, the thickness t of the ferromagnetic metal thin film in the vicinity of the magnetic gap g and the maximum magnetic field (apparent saturation magnetic field of the magnetic gap g) that can pass through the magnetic gap g. The result of having investigated the relationship of is shown. Similarly, FIG. 10 shows a magnetic head with L = 15 μm, and FIG. 11 shows a magnetic head with L = 20 μm.
This is the relationship between the thickness t of the ferromagnetic metal thin film in the vicinity of the magnetic gap g and the apparent saturation magnetic field of the magnetic gap g.

From FIGS. 9, 10 and 11, the smaller the thickness t of the ferromagnetic metal thin film, the smaller the magnetic field that can pass through the magnetic gap g, which is smaller than the saturation magnetic field that should originally pass through the magnetic gap g. You can see that it has ended. Comparing FIGS. 9, 10, and 11, the gap junction length L
The smaller the magnetic head, the greater the degree of decrease in the saturation magnetic field due to the decrease in the thickness t of the ferromagnetic metal thin film.

Therefore, in order to allow a large magnetic field to pass through the magnetic gap g in a magnetic head having a small gap junction length L, in other words, a small track width Tw, t should be at least as large as possible, at least t> L. It turns out that it is necessary.

Experiment 2 Next, the input / output characteristics of the magnetic head with t> L will be examined.

First, according to the method described in this embodiment, magnetic heads (magnetic heads A to F) having the gap junction length L and the thickness t of the ferromagnetic metal thin film near the magnetic gap g as shown in Table 1. It was created.

[0049]

[Table 1]

FIG. 12 shows the input / output characteristics of the magnetic head A and the magnetic head B, FIG. 13 shows the input / output characteristics of the magnetic head C and the magnetic head D, and FIG. 14 shows the input / output of the magnetic head E and the magnetic head F. The characteristics are shown respectively.

12, 13 and 14, the magnetic heads with t> L (magnetic heads B, D, F) are superior to the magnetic heads with t <L (magnetic heads A, C, D). It can be seen that it has input / output characteristics. In particular, in FIGS. 12 and 13, the effect of making the thickness t of the ferromagnetic metal thin film larger than the gap junction length L is great. From this, it is understood that it is preferable to make the thickness t of the ferromagnetic metal thin film larger than the gap junction length L in the magnetic head having the gap junction length L of 15 μm or less.

From the above experiments, in the case of a magnetic head having the same gap junction length L, the saturation magnetic field becomes larger as the thickness t of the ferromagnetic metal thin film becomes larger, and as a result, the magnetic field which is excellent in input / output characteristics is also increased. It turned out to be the head. In particular, in the magnetic head having the gap junction length L of 15 μm or less, it was found that the effect of increasing the thickness t of the ferromagnetic metal thin film to be larger than the gap junction length L is great.

[0053]

As is apparent from the above description, since the magnetic head of the present invention has a structure capable of sufficiently exhibiting the high saturation magnetic flux density Bs of the ferromagnetic metal thin film, the gap junction length L is small. In other words, even in a magnetic head having a small track width Tw, the saturation magnetic field in the magnetic gap portion becomes large, and excellent recording efficiency is exhibited. Therefore, by applying the present invention, it is possible to provide a magnetic head having excellent input / output characteristics.

[Brief description of drawings]

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

FIG. 2 is a front view showing a configuration example of a magnetic head of the present invention.

FIG. 3 is a perspective view showing the steps of manufacturing the magnetic head of the present invention in order, and showing the step of providing a kerf on the magnetic substrate.

FIG. 4 is a perspective view showing a step of forming a ferromagnetic metal thin film.

FIG. 5 is a perspective view showing a step of filling a non-magnetic material.

FIG. 6 is a perspective view showing a step of providing a second kerf.

FIG. 7 is a perspective view showing a step of providing a winding groove and an H groove.

FIG. 8 is a perspective view showing a process of butting and joining core blocks.

FIG. 9 is a characteristic diagram showing the relationship between the saturation magnetic field and the thickness t of the metal magnetic thin film in the vicinity of the magnetic gap g of the magnetic head in which the gap junction length L is set to 10 μm.

FIG. 10 is a characteristic diagram showing a relationship between the saturation magnetic field and the thickness t of the metal magnetic thin film in the vicinity of the magnetic gap g of the magnetic head in which the gap junction length L is set to 15 μm.

FIG. 11 is a characteristic diagram showing a relationship between the saturation magnetic field and the thickness t of the metal magnetic thin film near the magnetic gap g of the magnetic head in which the gap junction length L is set to 20 μm.

FIG. 12 is a characteristic diagram showing a relationship between a recording current and a relative output for a magnetic head A and a magnetic head B.

FIG. 13 is a characteristic diagram showing a relationship between a recording current and a relative output for a magnetic head C and a magnetic head D.

FIG. 14 is a characteristic diagram showing the relationship between the recording current and the relative output of the magnetic heads E and F.

FIG. 15 is a perspective view showing a configuration example of a conventional magnetic head.

FIG. 16 is a front view showing a configuration example of a conventional magnetic head.

[Explanation of symbols]

 1, 2 ... Magnetic core halves 1a, 2a ... Ferromagnetic metal thin film forming surface 1b, 2b ... Notches 3 ... Ferromagnetic metal thin film 4, 5 ... Non-magnetic material 6, 7・ ・ ・ Winding groove 8 ・ ・ ・ Coil 10 ・ ・ ・ Abutting surface 20 ・ ・ ・ Magnetic substrate 21 ・ ・ ・ Cutting groove 21a ・ ・ ・ Ferromagnetic metal thin film forming surface 23 ・ ・ ・ Ferromagnetic metal thin film 24, 28 ... Nonmagnetic material 25 ... Second kerf 29 ... Core block

Claims (2)

[Claims] 1. A pair of core halves is provided with a groove having an inclined surface facing the abutting surfaces of the core halves, and the end faces of the ferromagnetic metal thin films formed on the inclined surfaces abut each other to form a magnetic gap therebetween. In the magnetic head as described above, the thickness of the ferromagnetic metal thin film measured in the vertical direction from the slope is larger than the gap junction length in the vicinity of the magnetic gap. 2. The magnetic head according to claim 1, wherein the gap junction length is 15 μm or less.