JPH0793706A - Magnetic head - Google Patents

Abstract

(57) [Abstract] [Purpose] In a magnetic head in which a magnetic gap is formed at the junction of magnetic thin films, the inductance of the magnetic circuit is reduced, the reproduction efficiency is improved, and high density recording and reproduction can be supported. . A magnetic thin film 3 is formed on the leading core 1, a magnetic thin film 24 is formed on the trailing core 22, and a magnetic gap G is formed at the joint between the magnetic thin films 3 and 24.
Are formed. Magnetic thin film 2 for the trailing core
4 has a length W2 shorter than the total core length W1, and a non-magnetic material block 2 such as a glass material is provided in the length W3 portion.
2a is joined. By reducing the length W2 of the magnetic thin film 24, the inductance of the magnetic circuit can be reduced, and the ratio of the reproduction output to the inductance, that is, the reproduction efficiency can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head used as a floating magnetic head in a hard disk drive, in which a magnetic thin film in a leading core and a magnetic thin film in a trailing core are bonded to each other by a magnetic field. The present invention relates to a magnetic head having a gap.

[0002]

2. Description of the Related Art FIG. 6 is a perspective view showing a levitation type magnetic head used in a conventional hard disk device with a surface facing a recording medium facing upward, and FIG. 7 is a magnetic gap formation of the magnetic head of FIG. It is a perspective view which expands and shows a part. The flying magnetic head H shown in FIG. 6 is a composite type in which the surface facing the recording medium has a two-rail shape, and the slider 1 as a leading core and the I-shaped core 2 as a trailing core joined to the slider 1. And have. Then, as shown in FIG. 7, the coil 7 is wound around the I-shaped core 2.

An air groove 1c is formed in the center of the surface of the slider 1 facing the recording medium, and two rails 1a and 1b are formed on both sides of the air groove 1c. Further, a groove 1d is formed on the front end surface of the slider 1, and this groove 1d is a space for winding the coil 7 around the I-shaped core 2. The slider 1 is constituted by joining non-magnetic core members A1 and A2 of ceramic material or the like, and the magnetic thin film 3 is formed at the joint portion between the core members A1 and A2.
Are formed. Similarly, the I-shaped core 2 is also constructed by joining non-magnetic core members B1 and B2 made of a ceramic material or the like, and a magnetic thin film 4 is formed at the joint between the core members B1 and B2. The magnetic thin films 3 and 4 are formed in a single layer or multiple layers by sputtering a soft magnetic material such as sendust or a microcrystalline magnetic material onto the core member.

As shown in FIG. 7, the I-shaped core 2 is adhered to the front end of the slider 1 by an adhesive glass material 5a. At this time, a molded glass material 5b is attached to the joint between the slider 1 and the I-shaped core 2. A magnetic gap G is formed at the junction of the two magnetic thin films 3 and 4 which are interposed and are linear along the recording medium moving direction (X direction). This magnetic head H is shown in FIG.
The upper surface of the figure faces the hard disk, levitates on the disk that rotates and moves in the X direction, and recording or reproduction is performed by the magnetic gap G. By forming a magnetic gap G at the junction between the magnetic thin films 3 and 4, high density recording / reproduction can be achieved.

[0005]

In this type of magnetic head, the reproduction output is proportional to the number of turns (t) of the coil 7. On the other hand, the inductance L of the magnetic circuit formed by winding the coil 7 around the magnetic thin film 4 is proportional to the square of the number of turns (t) of the coil 7. The resonance frequency of the inductance L and the capacitance component C of this magnetic circuit is inversely proportional to the square root of the inductance L. The resonance frequency must be set to a band sufficiently higher than the frequency of the recording or reproducing signal by the magnetic head,
For example, when attempting to perform high-density recording / reproduction of about 15 MHz, it is necessary to set the resonance frequency to a high band of 30 MHz or higher. As described above, when the volume of the magnetic thin film 4 is constant, the larger the number of turns (t) of the coil 7, the higher the inductance L of the magnetic circuit and the lower the resonance frequency.
On the other hand, when the number of turns (t) of the coil 7 is reduced, the inductance L decreases, but the reproduction output decreases.

In a magnetic head having such contradictory elements, increasing the ratio of the reproduction output to the inductance of the magnetic circuit as much as possible leads to improvement in reproduction efficiency. However, the length W of the I-shaped core 2 in the X direction cannot be reduced so much because of the strength of the I-shaped core and the manufacturing process of the magnetic head H as a whole. There is a limit to how small the volume can be. Therefore, in the conventional magnetic head H shown in FIGS. 6 and 7, the inductance of the magnetic circuit tends to increase, and there is a limit in increasing the reproduction efficiency.

The present invention solves the above-mentioned problems of the prior art by providing a magnetic head in which the overall shape of the magnetic head can be maintained as it is and the inductance of the magnetic circuit can be reduced to improve the reproduction efficiency. It is intended to be provided.

[0008]

According to the present invention, there are provided a leading core in which a magnetic thin film extending in the moving direction of a recording medium is sandwiched between non-magnetic core members, and a magnetic thin film also extending in the moving direction of the recording medium. A trailing core that is sandwiched between non-magnetic core members and has a coil wound around it, and a magnetic gap is formed at the joint between the magnetic thin film in the leading core and the magnetic thin film in the trailing core. In the head, the length of the magnetic thin film in the trailing core is shorter than the total length of the trailing core in the recording medium moving direction.

In the above means, the length of the magnetic thin film in the trailing core is preferably 20 μm or more and 150 μm or less.

[0010]

In the above means, the length of the magnetic thin film in the trailing core in the moving direction of the recording medium is made shorter than the entire length of the trailing core, so that the structural strength of the trailing core is not lowered. It is possible to reduce the inductance L of the magnetic circuit for a predetermined number of turns of the coil. Therefore, the ratio of the reproduction output to the inductance, that is, the reproduction efficiency can be increased.

In particular, by setting the length of the magnetic thin film in the trailing core to 20 μm or more and 150 μm or less,
The optimum regeneration efficiency can be secured.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 is a perspective view showing a first embodiment of a magnetic head according to the present invention with a surface facing a recording medium facing upward, FIG. 2 is a perspective view showing a second embodiment of the magnetic head, and FIG. It is an expansion perspective view which shows a magnetic gap part. In the magnetic head H1 shown in FIG. 1, the shape and structure of the slider 1 serving as the leading core are the same as those of the conventional example shown in FIG. That is, non-magnetic core members A1 and A2 such as ceramic materials
A magnetic thin film 3 of a soft magnetic material is formed on the surface of the slider 1 that is joined to the recording medium, and an air groove 1c and rails 1a and 1b are formed on the surface of the slider 1 facing the recording medium. A groove 1d is formed on the front end surface.

The overall shape and dimensions of the I-shaped core 22 as the trailing core shown in FIG. 1 are the same as those of the I-shaped core 2 shown in FIG.
Therefore, the total length W1 of the I-shaped core 22 along the moving direction (X direction) of the recording medium is the I-shaped core 2 shown in FIG.
Has the same size as the total length W of. However, the structure of the I-shaped core 22 is different from that of the I-shaped core 2, and in the portion of the length W2, the magnetic thin film 24 of the soft magnetic material is formed on the joint surface between the non-magnetic core members Ba and Bb such as a ceramic material. Are formed. The remaining length W3 is the core members Ba and Bb.
A non-magnetic material block 22a such as a glass material different from that is joined. The I-shaped core 22 can be manufactured by bonding a glass material to a long block body in which a magnetic thin film is interposed at a constant pitch between ceramic materials or the like, and cutting this out in a width Y dimension. In the same manner as shown in FIG. 7, the I-shaped core 22 is made of the adhesive glass material 5a, and
Of the I-shaped core 22 and the slider 1 with a molded glass material 5b interposed therebetween, and a magnetic gap G is formed at the joint between the magnetic thin film 3 and the magnetic thin film 24. .

The I-shaped core 32 in the magnetic head H2 of the second embodiment shown in FIGS. 2 and 3 is not provided with the non-magnetic material block 22a such as a glass material. This I-type core 32
Has core members B1 and B2 made of the same ceramic material or the like as shown in FIG.
A magnetic thin film 34 of a soft magnetic material is interposed only in a portion having a length W2 along the direction, and a nonmagnetic film 35 made of a glass material or the like is interposed in a portion having a length W3. This I-shaped core can be formed by sputtering and laminating the magnetic thin film 34 and the non-magnetic thin film 35 on one of the core members B1 and B2, and then laminating the other core member on this. As described above, in each of the above-described embodiments, the magnetic thin film 24 or 3 is formed in the I-shaped core 22 or 32 which is the trailing core.
4 has a length W2 in the X direction shorter than the total length W1 of the I-shaped core. Therefore, the inductance of the coil 7 (same as FIG. 7) wound around the I-shaped core 22 or 32 for a fixed number of turns is smaller than that of the conventional magnetic head H shown in FIG. Therefore, the magnetic heads H1 and H2 of each embodiment
Then, the ratio of the reproduction output to the inductance, that is, the reproduction efficiency is improved as compared with the conventional magnetic head H. In this magnetic head with high reproduction efficiency, even if the number of turns of the coil is increased and the reproduction output is increased, the inductance is low, so that the resonance frequency of the magnetic circuit can be increased and high density recording and reproduction can be supported. .

Next, FIGS. 4 and 5 show the length W2 of the magnetic thin film 24 or 34 in the I-shaped core 22 or 32.
It is a measurement result showing the relationship between and the regeneration efficiency. In this measurement, a magnetic head having a non-magnetic material block 22a as shown in FIG. 1 was used. The magnetic thin film 3 in the slider (leading core) and the I-shaped core (trailing core)
Microcrystalline magnetic materials were used as and. The magnetic flux density was 1.4 (T; Tesla), and the magnetic permeability for an alternating current signal of 1 MHz was 3000. The film thickness of the magnetic thin films 3 and 24 was 6 μm.

FIG. 4 shows the relationship between the length L2 of the magnetic thin film in the I-shaped core (trailing core) and the inductance L0 (solid line graph) of the magnetic circuit and the normalized reproduction output (dotted line graph). There is. The inductance L0 here is the inductance (nH; to the square (t ² ) of the number of turns (t) of the coil wound around the I-shaped core.
Nano-Henry), that is, (nH / t ² ). The standardized reproduction output means that the length W is 200.
This means the ratio of the reproduction output when the reproduction output at μm is “1”.

Looking at the standardized reproduction output in FIG.
It can be seen that the peak of W2 is 50 μm or more, and the reproduction output cannot be improved even if W2 is increased more than that. on the other hand,
The inductance L0 increases as the length W2 of the magnetic thin film increases. Therefore, when trying to obtain a high reproduction output without increasing the inductance, it is understood that the length W2 of the magnetic thin film is most preferably around 50 μm. Therefore, in FIG. 5, the horizontal axis represents the length W2 of the magnetic thin film, and the vertical axis represents the reproduction efficiency. This reproduction efficiency is based on the result of FIG. 4 and shows (normalized reproduction output) / (L0) ^1/2 , that is, the ratio of the normalized reproduction output to the square root of the inductance L0. Here, (L0) ^1/2 is set because the inductance L0 is related to the square of the number of turns of the coil (t ² ),
This is because the normalized reproduction output is proportional to the number of turns (t), so that the dimensions of the denominator and the numerator are matched.

In FIG. 5, as described above, it can be confirmed that the reproducing efficiency has a peak when the length W2 of the magnetic thin film is 50 μm. In addition, the regeneration efficiency W is almost "1" or more.
When the range of 2 is determined, it is 20 μm or more and 100 μm or less, and it is most preferable to set W2 to this range. See also W
It is understood that when 2 is 20 μm or more and 150 μm or less, a sufficiently high regeneration efficiency can be obtained. It should be noted that, even if a general magnetic head of this type has the structure shown in FIG. 1 or the like, or has a shape with an I-shaped core in the center of the slider, the dimensions of the I-shaped core, that is, the trailing core are almost the same. Further, since there is no great difference in the magnetic flux density and the film thickness of the magnetic thin film, it is considered that the above range of W2 can be applied to any magnetic head of this type.

[0019]

As described above, according to the present invention, by shortening the length of the magnetic thin film in the trailing core, it is possible to increase the ratio of the reproduction output to the inductance of the magnetic circuit, that is, the reproduction efficiency. It is possible to obtain a magnetic head most suitable for recording and reproducing.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a magnetic head of the present invention with a surface facing a recording medium facing upward;

FIG. 2 is a perspective view showing a second embodiment of the magnetic head of the present invention with the surface facing the recording medium facing upward;

FIG. 3 is an enlarged perspective view showing a magnetic gap portion of the embodiment of FIG.

FIG. 4 is a diagram showing the relationship between the length of the magnetic thin film in the trailing core, the inductance, and the normalized reproduction output.

FIG. 5 is a diagram showing the relationship between the length of the magnetic thin film in the trailing core and the reproduction efficiency,

FIG. 6 is a perspective view showing a conventional magnetic head,

7 is an enlarged perspective view showing a part of the magnetic head shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 slider (leading core) 3 magnetic thin film 22,32 I type core (trailing core) 24,34 magnetic thin film 22a non-magnetic material block G gap part A1, A2, B1, B2, Ba, Bb core member H1, H2 Magnetic head W1 Total length of trailing core W2 Length of magnetic thin film in trailing core

Front page continued (72) Inventor Hiroe Tonsho 1-7 Yukiya Otsukacho, Ota-ku, Tokyo Alps Electric Co., Ltd.

Claims (2)

[Claims] 1. A leading core in which a magnetic thin film extending in a moving direction of a recording medium is sandwiched between non-magnetic core members,
Similarly, the magnetic thin film extending in the moving direction of the recording medium has a trailing core sandwiched between non-magnetic core members and wound with a coil, and the magnetic thin film in the leading core and the magnetic thin film in the trailing core. In the magnetic head in which a magnetic gap is formed at the junction of the magnetic head, the length of the magnetic thin film in the trailing core is formed to be shorter than the total length of the trailing core in the recording medium moving direction. head. 2. The magnetic head according to claim 1, wherein the length of the magnetic thin film in the trailing core is 20 μm or more and 150 μm or less.