JPH07210816A - Magnetic head - Google Patents

Abstract

(57) [Summary] [Purpose] Securing a good sliding state between the magnetic head and the magnetic recording medium and securing the cross-sectional area of the magnetic core even when the sliding surface of the medium wears at least to the depth zero position of the magnetic gap. To improve the regeneration efficiency. In a magnetic head in which a pair of magnetic core halves 1 and 2 are joined and integrated by a fused glass 3 and a magnetic gap g is formed between abutting surfaces, a width of a medium contact surface 7 exhibited by the magnetic gap g. The step portions 5 and 6 for regulating the depth are made deeper than the medium sliding surface when the medium sliding surface 7 is worn to the depth zero position, and the medium sliding when the medium sliding surface is worn to the depth zero position. It is formed in an arc shape having a curvature substantially parallel to the surface or smaller than the curvature of the medium sliding surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head mounted in a recording / reproducing apparatus such as a video tape recorder, and more particularly, it has a step portion on a medium sliding surface for regulating a contact width with a magnetic recording medium. The present invention relates to the structure of a magnetic head.

[0002]

2. Description of the Related Art In the field of magnetic recording, it is needless to say that a manufacturing technique for manufacturing a cheaper magnetic head is required, and a magnetic head and a magnetic recording for the purpose of good recording and reproduction. There is a demand for a magnetic head having a structure that optimizes sliding (contact) with a medium.

Under these circumstances, in the magnetic head, the width of the medium sliding surface that slides on the magnetic recording medium is regulated in order to improve the workability or to make the sliding condition with the magnetic recording medium favorable. Attempts have been made to do so. Specifically, step grooves are formed on the medium sliding surfaces on both sides of the magnetic gap so as to leave the track width portion of the magnetic gap, and the step grooves regulate the width of the medium sliding surface.

However, it is known that when the stepped groove is formed on the medium sliding surface, the reproduction output characteristic is deteriorated due to the decrease of the magnetic core cross-sectional area. Therefore, it is desirable to make the depth of the step groove as shallow as possible.

On the other hand, it is well known that the medium sliding surface is machined so as to have an appropriately arcuate surface so that the magnetic head and the magnetic recording medium can slide well. When the medium sliding surface is arcuate and the bottom of the step groove is linear,
It is necessary to deepen the stepped groove processing so that the sliding state between the magnetic recording medium and the magnetic head does not change even after the head wear has progressed.

As described above, in order to improve the sliding state between the magnetic head and the magnetic recording medium, it is necessary to form a step groove on the medium sliding surface and to make the medium sliding surface arcuate. Is effective, but the depths of the stepped grooves are contrary to each other.
These will be described below with reference to the drawings.

FIG. 10 is a perspective view of a conventional magnetic head. This magnetic head has a pair of magnetic core halves 101 and 102 made of ferrite or the like, and the magnetic core halves 101 and 102 are fused to each other via a gap film.
A magnetic gap g functioning as a recording / reproducing gap is formed between these abutting surfaces by being joined and integrated by 03.

The track width Tw of the magnetic gap g is shown in FIG.
As shown in FIG. 1, a step groove 104 formed to improve the sliding characteristics between the magnetic head and the magnetic recording medium,
It is regulated by 105. Step grooves 104, 105
At the both ends of the magnetic gap g in the track width direction, a portion of the medium sliding surface 106, which is in an arc shape and is in sliding contact with the magnetic recording medium with respect to the core width Cw of the entire head, is cut out so that the magnetic It is formed as a straight groove perpendicular to the direction in which the core halves 101, 102 are abutted with each other.

On the other hand, the depth d of the magnetic gap g is shown in FIG.
As shown in FIG. 2, it is regulated by the inclined surface 107 a of the winding groove 107 for coil winding formed on the abutting surface of the one magnetic core half body 101.

[0010]

By the way, in the magnetic head having the above structure, as described above, the step grooves 104, 105 are formed.
As the depth h increases, the reproduction output characteristic of the magnetic head decreases due to the decrease in the core cross-sectional area. For this reason, it is desirable that the depth δ from the position where the depth d of the magnetic gap g becomes zero be as small as the manufacturing convenience allows.

However, the step grooves 104 and 105 are formed.
Is formed linearly, the stepped grooves 104, 10
If the depth h from the medium sliding surface 106 of No. 5 is reduced, and the depth d of the magnetic gap g is reduced due to wear due to sliding contact between the magnetic head and the medium, the sliding surface shape as shown in FIG. Therefore, a good sliding state with the magnetic recording medium cannot be obtained. In other words, the step groove 10 due to wear
Even Nos. 4 and 105 are worn, and the contact characteristics with respect to the magnetic recording medium change. Therefore, the step grooves 104 and 10
There was a limit to reducing the depth h of 5.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-described problems of the prior art, the present invention provides a magnetic head and a magnetic recording medium even when the medium sliding surface is worn to at least the depth zero position of the magnetic gap. It is an object of the present invention to provide a magnetic head having a high reproduction efficiency, in which a good sliding state can be obtained and a magnetic core cross-sectional area is secured.

[0013]

The magnetic head of the present invention comprises:
It has a pair of magnetic core halves made of an oxide magnetic material, these magnetic core halves are joined and integrated, and a magnetic gap is provided between their abutting surfaces. Then, there are stepped portions on both sides of this magnetic gap in the track width direction,
The stepped portion regulates the width of the medium sliding surface that is in sliding contact with the magnetic recording medium. Further, in this magnetic head, the above problem is solved by making the bottom surface of the step portion deeper than the medium sliding surface when the medium sliding surface is worn to the depth zero position of the magnetic gap.

Further, according to the present invention, the bottom surface of the step portion is substantially parallel to the medium sliding surface or the medium sliding surface when the medium sliding surface having an arc shape is worn to the depth zero position of the magnetic gap. By making the curvature smaller than the curvature of the moving surface,
The above problems are solved.

Further, in the magnetic head of the present invention, the magnetic core half body may be made of a single oxide magnetic material, or may be a composite of an oxide magnetic material and a metal magnetic thin film. Further, the stepped portion may be filled with a non-magnetic material having excellent wear resistance.

[0016]

According to the present invention, the bottom surface of the step portion that regulates the width of the medium sliding surface is made deeper than the medium sliding surface when the medium sliding surface is worn to the depth zero position of the magnetic gap. Therefore, the sliding state between the magnetic head and the magnetic recording medium is substantially constant until at least the depth zero position, and good sliding characteristics can be obtained. Therefore, the reproduction output is almost constant until the end of the life of the head.

In particular, the shape of the bottom surface of the step portion is set to be substantially parallel to the medium sliding surface when the medium sliding surface is worn to the depth zero position of the magnetic gap or a curvature smaller than the curvature of the medium sliding surface. Has ensured the cross-sectional area of the magnetic core,
A change in the sliding state between the magnetic head and the magnetic recording medium is suppressed up to the depth zero position, and good sliding characteristics can be obtained.

[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. In the magnetic head of this embodiment, as shown in FIG. 1, magnetic core halves 1 and 2 made of an oxide magnetic material such as Mn—Zn based ferrite or Ni—Zn based ferrite are joined and integrated by a fused glass 3. It will be.

A winding groove 4 for winding a coil is formed in one magnetic core half body 1 forming a closed magnetic circuit. The winding groove 4 is formed in the core thickness direction as a groove having a substantially U-shaped cross section on the abutting surface of the magnetic core halves 1 and 2.

Of the winding groove 4, the inclined surface 4a formed on the side close to the magnetic gap g serves to regulate the depth d of the magnetic gap g, as shown in FIG. ing.

The magnetic gap g in this magnetic head is a gap spacer (not shown) made of a nonmagnetic material on the abutting surfaces of the magnetic core halves 1 and 2.
By sandwiching and abutting, the magnetic core halves 1 and 2 are formed between the abutting surfaces.

The medium sliding surface 7 exhibited by the magnetic gap g.
Has an arc shape with the magnetic gap g portion as the apex in order to make the sliding state between the magnetic head and the magnetic recording medium favorable.

The track width T of the magnetic gap g is
Like the medium sliding surface 7, w is regulated by the step portions 5 and 6 formed to secure the contact between the magnetic head and the magnetic recording medium. The step portions 5 and 6 are formed at both ends of the magnetic gap g in the track width direction by scraping off a part of the medium sliding surface 7.
Therefore, the medium sliding surface 7 projects to the central portion of the core thickness with the track width Tw of the magnetic gap g.

Further, the step portion 5 from the medium sliding surface 7 is
As shown in FIG. 2, the depth h of 6 is made slightly deeper than the depth d zero position of the magnetic gap g (the tip position of the inclined surface 4a of the winding groove 4).

Further, the bottom surfaces 5a, 6 of the step portions 5, 6 are
The shape of a is an arc having a curvature substantially the same as the curvature of the medium sliding surface 7. Therefore, the bottom surfaces 5a and 6a of the step portions 5 and 6 are parallel to the medium sliding surface 7.

In the magnetic head constructed as described above, the medium sliding surface 7 is gradually polished by the sliding contact between the magnetic head and the magnetic recording medium, and finally the magnetic gap g as shown by the broken line in FIG. The depth d of is cut to the zero position. Even if the medium sliding surface 7 is scraped to the depth d zero position, since the step portions 5 and 6 are deeper than the depth d zero position, the sliding state between the magnetic head and the magnetic recording medium is Almost no change from the initial state to the end of the head life.

The bottom surfaces 5a and 6a of the step portions 5 and 6 are
Since it has an arc shape with a curvature substantially the same as the curvature of the medium sliding surface 7, it is possible to secure a sufficient cross-sectional area of the ferrite that contributes to the magnetic path. Therefore, the reduction in reproduction output is improved as compared with the magnetic head shown in FIG.

Normally, the radius of curvature of the medium sliding surface 7 gradually increases due to abrasion due to the sliding contact between the magnetic head and the magnetic recording medium. FIG. 2 shows the state of the medium sliding surface 8 when the medium sliding surface 7 is worn to the depth d zero position of the magnetic gap g by a broken line. The curvature of the medium sliding surface 8 at the depth d zero position becomes larger than the initial curvature of the medium sliding surface 7 due to wear.

Therefore, in the magnetic head of this embodiment,
Since the curvatures of the bottom surfaces 5a and 6a of the step portions 5 and 6 are the same as the curvature of the initial medium sliding surface 7, they are arcuate.
Even if the depth δ from the depth d zero position to the bottom surfaces 5a and 6a is substantially zero, the medium sliding surface 7 will be in a good sliding state even if it is worn from the initial state to the depth d zero position. Obtainable. From this, it is possible to manufacture a magnetic head in which the depth h of the step portions 5 and 6 is substantially equal to the depth d of the magnetic gap g.

In the above example, since the medium sliding surface 7 gradually wears due to the sliding contact with the magnetic recording medium and its radius of curvature increases, the bottom surfaces 5a, 6 of the step portions 5, 6 are increased.
Although a is an arc shape having a radius of curvature substantially the same as that of the initial medium sliding surface 7, the point is that the curvature of the bottom surfaces 5a and 6a is greater than the curvature of the medium sliding surface 8 when it is worn to the depth d zero position. If it is made small, the object of the present invention can be achieved.

Further, in the above-mentioned embodiment, the magnetic path is composed of ferrite alone. However, in addition to ferrite, a so-called metal-in-gap in which a metal magnetic film having a high saturation magnetic flux density is arranged in the vicinity of the magnetic gap g. A similar type of magnetic head can also be obtained.

FIG. 3 shows a magnetic head in which the abutting surfaces of the magnetic core halves 1 and 2 are formed into a substantially trapezoidal shape, and the metal magnetic films 9 and 10 are formed on the abutting surfaces. In FIG. 4, the abutting surfaces of the magnetic core halves 1 and 2 are formed into a pointed shape, the metal magnetic films 11 and 12 are formed on one inclined surface of the abutting surfaces, and the magnetic films obtained by abutting these oblique films together Shows the head.

The magnetic head shown in FIGS. 3 and 4 is
Although both the left and right magnetic core halves 1 and 2 are made of an oxide magnetic material and a metal magnetic film, only one of the magnetic core halves is made of an oxide magnetic material and a metal magnetic film, and the other magnetic core half is made of an oxide magnetic material and a metal magnetic film. The core half may be made of only the oxide magnetic material.

Further, in the above example, the bottom surfaces 5a and 6a of the step portions 5 and 6 are formed to have an arc shape, but they may have a shape as shown in FIG. 5, for example. That is, the stepped portions 13 and 14 are straight surfaces 13a perpendicular to the magnetic gap g in the vicinity of both sides of the magnetic gap g with respect to the shape of the medium sliding surface 7 having an arc shape (the other straight surface is shown). Is omitted.) Both sides of the straight surface 13a are inclined surfaces 13b and 14b such that the groove depth gradually becomes deeper in the direction opposite to the direction in which the magnetic core halves 1 and 2 are abutted with each other. Of course, these steps 1
3 and 14 are deeper than the medium sliding surface when worn until the depth d of the magnetic gap g becomes zero.

Thus, if the bottom surfaces of the step portions 13 and 14 are composed of the straight surface 13a and the inclined surfaces 13b and 14b and have a shape close to an arc like the head of FIG. 1, the magnetic core cross-sectional area is secured. In addition, even when the medium sliding surface 7 is worn to the depth d zero position of the magnetic gap g, the sliding state with the magnetic recording medium can be made substantially constant until the life of the head.

Further, the step portion 5, of the magnetic head shown in FIG.
As shown in FIG. 6, 6 may be filled with a non-magnetic wear resistant material 15 for the purpose of improving wear resistance of the magnetic head. The non-magnetic abrasion resistant material 15 is, for example, SiC, ZrO ₂ , A which is hard to be abraded by sliding contact with the magnetic recording medium.
_{l 2 O 3, Al 2 O} 3 -TiC, TiO 2, NiO-C
aTiO _{3 and the} like are preferable.

In addition, as shown in FIG. 7, a magnetic core half body in which metal magnetic films 16 and 17 having a single-layer or laminated film structure are sandwiched between a pair of non-magnetic substrates 18 and 19 from the thickness direction thereof. The magnetic heads 20 and 21 may be applied to a magnetic head in which the metal magnetic films 16 and 17 present on the abutting surfaces are abutted to each other and joined by the glass 3. That is, an arc-shaped step portion 2 formed in the same manner as the magnetic head shown in FIG.
2, 23 may be filled with a non-magnetic abrasion resistant material 24.

Next, the present inventors actually prepared a magnetic head for a video tape recorder under the following conditions and measured the reproduction output of the magnetic head.

Prototype Example 1 As shown in FIG. 8, the abutting surfaces of a pair of magnetic core halves 25, 26 made of Mn-Zn ferrite are formed in a substantially trapezoidal shape, and these magnetic core halves 25, 26 are joined together. The glass 27 was joined and integrated through the gap spacer. Then, the medium sliding surface 2 exhibited by the magnetic gap g
8 is an arc shape, and the bottom surfaces 29 of the step portions 29 and 30 are
The a and 30a are formed to have the same radius of curvature as the curvature of the medium sliding surface 28.

Here, the radius of curvature of the medium sliding surface 28 is set to 8
mm, the depth of the magnetic gap g is 20 μm, the step portion 2
The depth of 9, 30 was 30 μm.

Prototype Example 2 In Prototype Example 2, the same shape as the magnetic head of Prototype Example 1 was used except that the shape of the step portion was changed. That is, the step portion 31,
As shown in FIG. 9, 32 is formed as a straight groove perpendicular to the magnetic gap g, and its bottom surfaces 31a, 32 are formed.
a is a flat surface. Here, the radius of curvature of the medium sliding surface 28 was 8 mm, the depth of the magnetic gap g was 20 μm (similar to the magnetic head of Prototype Example 1), and the depths of the step portions 31 and 32 were 100 μm.

Then, using the magnetic heads of Prototype Examples 1 and 2, reproduction was performed on the magnetic tape. as a result,
The reproduction output of the magnetic head of Prototype Example 1 was improved by 0.5 dB as compared with the magnetic head of Prototype Example 2. In other words, the stepped portion formed to secure the contact with the magnetic recording medium is not a straight groove with a flat bottom surface, but the curvature of the medium sliding surface when the medium sliding surface is worn down to zero depth. The reproduction output can be increased by setting the curvature to the same value or less. Of course, the same applies to the magnetic head shown in FIG.

[0043]

As is apparent from the above description, in the magnetic head of the present invention, the stepped portion formed for making good contact with the magnetic recording medium has a magnetic gap depth of zero. Since it forms a curved surface that is substantially parallel to the medium sliding surface when worn down to a certain position or an arc shape with a curvature smaller than the curvature of the medium sliding surface, and is formed to a position deeper than the depth zero position, By increasing the cross-sectional area of the magnetic core in the vicinity of the gap, the reproduction efficiency of the magnetic head can be improved, and the sliding state between the magnetic head and the magnetic recording medium is almost the same as the initial state from the initial state to the depth zero position. Can be

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetic head including a step portion having a curvature substantially the same as that of a medium sliding surface.

FIG. 2 is an enlarged front view of essential parts showing a portion in the vicinity of a medium sliding surface of the magnetic head of FIG.

FIG. 3 is a perspective view showing an example of a metal-in-gap type magnetic head.

FIG. 4 is a perspective view showing another example of a metal-in-gap type magnetic head.

FIG. 5 is a perspective view of a magnetic head showing an example in which the groove shape of the step portion is formed by a straight surface and an inclined surface.

FIG. 6 is a perspective view of a magnetic head having a stepped portion filled with a non-magnetic abrasion resistant material.

FIG. 7 is a perspective view of a magnetic head in which a step portion of a metal-in-gap type magnetic head is filled with a non-magnetic abrasion resistant material.

8 is a perspective view of a magnetic head of Prototype Example 1. FIG.

9 is a perspective view of a magnetic head of Prototype Example 2. FIG.

FIG. 10 is a perspective view of a conventional magnetic head.

11 is an enlarged plan view of an essential part showing a portion near the magnetic gap of the magnetic head of FIG.

12 is an enlarged front view of essential parts showing a portion near the magnetic gap of the magnetic head of FIG.

13 is a perspective view showing a worn state of the magnetic head shown in FIG.

[Explanation of symbols]

 1, 2 magnetic core half body 3 fused glass 4 winding groove 5, 6 step portion 7 medium sliding surface d magnetic gap depth h depth of step portion from medium sliding surface to bottom surface

Claims (5)

[Claims] 1. A magnetic gap is formed between abutting surfaces of a pair of magnetic core halves made of an oxide magnetic material, and a step portion is provided on both sides of the magnetic gap in the track width direction. In the magnetic head in which the width of the medium sliding surface that is in sliding contact with the magnetic recording medium is restricted, the bottom surface of the step portion is more than the medium sliding surface when the medium sliding surface is worn to the depth zero position of the magnetic gap. A magnetic head characterized by being deepened. 2. A magnetic gap is formed between abutting surfaces of a pair of magnetic core halves made of an oxide magnetic material, and a step portion is provided on both sides of the magnetic gap in the track width direction. In a magnetic head in which the width of a medium sliding surface that is in sliding contact with a magnetic recording medium is restricted, the bottom surface of the stepped portion is an arc-shaped medium when the medium sliding surface is worn to the depth zero position of the magnetic gap. A magnetic head characterized by being substantially parallel to a sliding surface. 3. A magnetic gap is formed between abutting surfaces of a pair of magnetic core halves made of an oxide magnetic material, and a step portion is provided on both sides of the magnetic gap in the track width direction. In a magnetic head in which the width of the medium sliding surface that is in sliding contact with the magnetic recording medium is restricted, the bottom surface of the stepped portion has a curvature of the medium sliding surface when the medium sliding surface is worn to the depth zero position of the magnetic gap. A magnetic head having an arc shape with a smaller curvature. 4. A metal magnetic thin film is formed on at least one of the magnetic core halves.
4. The magnetic head according to claim 3. 5. The magnetic head according to claim 1, wherein the step portion is filled with a non-magnetic material.