JPS58224426A - Magnetic head - Google Patents

Abstract

PURPOSE:To use a magnetic head with a high line density by joining >=1 kind of soft magnetic materials having saturated magnetic flux density smaller than that of core materials on one or both sides of the butted surfaces of the core materials to form a gap. CONSTITUTION:When recording current is increased, the quantity of magnetic flux flowing into the core is also increased and the core materials 5, 5' are magnetically saturated at the saturated magnetic flux density value B's. When the recording current is increased more over, the core materials 6, 6' are saturated at a value Bs larger than B's. At this time, the maximum head field is generated, but the magnetic flux density is discontinued in the core like Bs and B's. Since the magnetic flux density is discontinuous, the head field can be interpreted as the sum of the magnetic field of a narrow gap length head and a wide gap length head. Namely, the magnetic head operates effectively as a recording head having wide gap length, so that the upper limit of the generated magnetic field intensity is raised.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head used for digital recording, and an object thereof is to realize a high-resolution magnetic head that can generate a strong magnetic field.

FIG. 1 shows the structure of a conventional magnetic head near the air gap. In FIG. 1, the first and second pieces are core materials constituting each head, and form a gap 3.

The operation of this head is such that the magnetic flux flowing through the excited core leaks to the outside due to the air gap 3, thereby generating a magnetic field to the outside and magnetizing the recording medium 4.2., -=. Generally, it is known that the maximum value of the magnetic field strength at this time increases as the gap length increases, provided that core fibers having the same saturation magnetic flux density are used. Therefore, it is desirable for the recording head to have a somewhat large gap length, but conversely, because of so-called gap loss during reproduction, high-resolution reproduction cannot be achieved unless the gap length is made small. Therefore, the essential property of a magnetic head with this structure is that the magnetic head for high linear density has a small head magnetic field strength during recording.

In principle, the above problem can be solved by constructing the magnetic head with a core material having a high saturation magnetic flux density. However, other properties that a head core material must possess include high magnetic permeability and good frequency characteristics.

It has wear resistance, low cost, etc., and when these factors are considered, the reality is that the saturation magnetic flux density value of practical core materials is relatively low.

As described above, conventional magnetic heads that can be used at high linear densities have had the drawback of weak recording head magnetic fields and inferior so-called overwriting characteristics.

The present invention eliminates the above-mentioned drawbacks of the conventional art, and one embodiment of the present invention will be described below with reference to FIG. 2.

In FIG. 2, 5, 5' and 6, 6' are core materials constituting the magnetic head, and the saturation magnetic flux density is 6.
A core material 6.5', which is smaller than e', is bonded in advance to the abutting surfaces of the core materials 6.5' to form the lower gap.

Next, the operation of the embodiment 1 will be explained.

When the recording current is increased, the amount of magnetic flux flowing in the core increases, and first the core material 6.6' becomes magnetically saturated at its saturation magnetic flux density value J.sub.2. By further increasing the recording current, the core material is 6.6
′ reaches a value BS larger than the value BS and reaches saturation. At this time, the maximum head magnetic field is generated, but inside the core, BS
A discontinuity in the magnetic flux density of B6 and B6 occurs.

FIG. 3 explains the head magnetic field in the above state. Because of the discontinuity in magnetic flux density, the head magnetic field can be interpreted as the sum of the magnetic fields of the narrow gap length head and the wide gap length head. That is, the upper limit of the magnetic field strength that can be generated to effectively operate as a wide gap length recording head is high.

FIG. 4 shows the results of an approximate calculation of this effect. Fourth
The figure shows the percentage increase in maximum head flux compared to a conventional head with the same air gap length (see FIG. 1). However, the numerical values used here are set as an example that is considered to be practical.

From FIG. 4, the upper limit of the head magnetic field strength increases to about i50 to 200% compared to the conventional magnetic head.

On the other hand, in the reproduction operation of the head of this embodiment, since the amount of magnetic flux handled is small, both the core materials 6.6' and 6,6' do not reach saturation, and the gap length is determined by the mechanical Limited by the dimensions of the non-magnetic part itself.

Therefore, during reproduction, it operates as a high resolution, narrow gap length head.

As described above, the above-mentioned embodiment has the advantage that it exhibits high resolution as a narrow gap length head during reproduction, and generates a strong head magnetic field during recording, resulting in excellent overwriting characteristics.

FIG. 6 shows a second embodiment of the invention.

In this case, it is an asymmetric structure in which the core material 8 having a low saturation magnetic flux density is formed only on one side of the core material 9 and 9' having a high saturation magnetic flux density. The degree of improvement in this second embodiment is as shown in FIG. Note that FIG. 6 is shown following FIG. 4. Although the effect is slightly lower than that of the previous embodiment, it has the advantage of being easier to manufacture.

In this asymmetric structure, the magnetic field distribution is also asymmetric.

However, as is clear from magnetic recording theory, the magnetic field distribution on the trailing edge (the gap edge through which the recording point passes later) side is important during recording. Therefore, as will be described later, if the joining surface of different types of cores is used as the leading edge (the edge of the gap through which the recording point passes first), a more desirable recording head magnetic field distribution will be obtained.

On the other hand, it is also required that the gradient of the magnetic field generated by the magnetic head be steep.

Figure 7 Fa), (b) and Figure 8 (a), (b)
) are calculated head magnetic field distributions during recording for the 6 pages of the first example and the second example shown in FIGS. 2 and 5, respectively. (Al and (b) have different values for the distance y from the head surface. Also, in Figures 7 and 8, the figures are normalized by the maximum value of the magnetic field strength in a head with a conventional structure. Note that the coordinate system is as shown in the figure.

From Figures 7 and 8, the following conclusion can be drawn.

(a) In the magnetic head of the present invention, the gradient of the head magnetic field is not significantly degraded compared to the conventional magnetic head. Particularly in the useful strong magnetic field region, the steepness of the gradient is almost the same as that of conventional magnetic heads.

(b) The rate of increase in magnetic field strength becomes more significant as the distance from the head surface increases (as y increases). This is desirable from the perspective of allowing the head magnetic field to penetrate into the back side of the medium magnetic layer, which is important for overwriting characteristics.

e→In the asymmetric structure head (second embodiment) shown in FIG.
When the joining surface of different types of cores is used as the leading edge, the side where the gradient of the head magnetic field is steep can be used as the trailing edge, so that a more desirable head magnetic field distribution with a 7-bene angle can be achieved.

The configuration and operation of the present invention have been described above, and according to the present invention, the following effects can be obtained.

(a) Since a stronger magnetic field can be generated when the air gap length during reproduction is effectively the same as that of a conventional head, a magnetic head for digital recording that can be used at high linear density and has excellent overwriting characteristics can be realized. .

(b1) To manufacture the magnetic head of the present invention, it is sufficient to use the same method as the conventional head manufacturing method, except for attaching a different type of core to the core material using a thin film manufacturing technique such as sputtering. can be produced.

Although only two embodiments have been shown here, various modifications can be made in line with the idea of constructing the head with two or more types of core materials having different saturation magnetic flux densities.

However, the numbers shown here are just examples.
It can be optimized depending on the application.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the vicinity of the air gap of a conventional magnetic head, FIG. 2 is a perspective view of the vicinity of the air gap of a magnetic head according to the first embodiment of the present invention, and FIG. 3 is a schematic diagram explaining the operation of the magnetic head. Figure 4 is a diagram showing the maximum head magnetic field of the same magnetic head,
FIG. 5 is a perspective view of the vicinity of the air gap of the magnetic head in a second practical example of the present invention, FIG. 6 is a diagram showing the maximum head magnetic field of the same example, FIGS. 7(a), (b), and 8. (a) (b)
1 is a diagram showing the magnetic field distribution of the magnetic heads of the first and second embodiments, respectively. 5.5', 6.6'...Core material, End...Gap, 819.9'...Core material. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
20 4 Figure 3 Figure 5 Figure 7 7rl!X 7//

Claims (1)

[Claims] The gap is formed by attaching one or more soft magnetic materials having a saturation magnetic flux density smaller than the saturation magnetic flux density of the core material to one or both of the abutting surfaces of the core material forming the gap. magnetic head.