JPH07118053B2 - Magnetic head - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic head of a magnetic recording / reproducing apparatus.

(Structure of Conventional Example and Problems Thereof) Generally, as a head core material of a magnetic head, an alloy material such as permalloy, sendust and alpalm, or ferrite is used. Of these head core materials, ferrite has the highest wear resistance, but the saturation magnetic flux density is 30% to 50% compared to the above alloy materials.
The alloy material is lower in wear resistance than ferrite but is excellent in saturation magnetic flux density.

On the other hand, although various recording media are used,
Recently, a high-density recording medium with high coercive force has been proposed,
When this is used, a material having a high saturation magnetic flux density is required so that the head core of the magnetic head does not cause magnetic saturation. For this reason, ferrite is not suitable as the head core material of the magnetic head compatible with the above high-density recording medium, but alloy material is suitable. However, the alloy material is originally poor in wear resistance, and the track width is reduced to around 20 μm in high density recording as in recent years, and accordingly, it is necessary to reduce the width near the gap portion of the head core. However, there is a problem in terms of wear resistance.

Therefore, conventionally, there has been proposed a magnetic head having improved wear resistance by sandwiching a head core made of an alloy material with a substrate made of a non-magnetic material having good wear resistance to form a laminated structure. Further, although it is known that the magnetic head having such a laminated structure is suitable for the head core material, it is not possible to obtain a thin one such as a ribbon shape, which delays its practical use. It is possible to use a different amorphous metal for the head core.

However, in the magnetic head having such a laminated structure,
Since the substrate material has better wear resistance than the head core material, when the head front surface is polished, the head core falls from the substrate and so-called uneven wear occurs. When this uneven wear occurs, the contact between the magnetic tape and the magnetic head deteriorates, and the spacing loss significantly reduces the output, especially on the order of MHz. The head output drops by a few dB with Å.

Actual uneven wear due to head front polishing is 200Å or 4
It is about 00Å. Various head shapes have been proposed as shown in FIG. 1 as a method for improving the contact between the head and the tape for the purpose of reducing the spacing loss as much as possible.

FIG. 1 (a) shows a sharpened tip in the width direction of the tip of the head, FIG. 1 (b) shows a sharpened portion near the head gap, and FIG. 1 (c) shows a reduced head width. All of these structures have good head and tape contact,
Although it is advantageous in terms of head output, it is inferior in terms of head wear. That is, since the contact width in the tape sliding direction is extremely small, there is a drawback that the wear resistance is mainly determined by the thickness of the head chip.

(Object of the Invention) The object of the present invention is to eliminate the drawbacks of the prior art, to improve the contact state between the magnetic tape and the head, to eliminate spacing loss,
A magnetic head capable of maintaining a high head output level from the initial state to running for a long time.

(Structure of the Invention) A magnetic head of the present invention has a sandwich structure in which a head chip sandwiches a magnetic material constituting a head core with a substrate from both sides, and the material of this substrate has higher wear resistance than the material of the magnetic material. In addition, the radius of curvature R (hereinafter simply referred to as R) in the chip thickness direction on the tape sliding surface of the head chip that is in contact with the magnetic tape is 0.2 to 1 mm at the initial stage of equipment attachment.

(Description of Embodiments) An embodiment of the present invention will be described with reference to FIGS. 2 to 6.

A magnetic head having a laminated structure is generally shown in FIG.
As shown in (b), it is formed of a laminated body in which a head core 1 which is a magnetic body having a desired track width and is sandwiched between substrates 2 and 2'which are non-magnetic bodies. 3 is a winding window.

An amorphous alloy or a sendust alloy is suitable as the material of the head core 1. The material of the substrates 2 and 2'is preferably a non-magnetic material that is dense and hard, has good wear resistance against a magnetic tape, and has a coefficient of thermal expansion as close to that of the material of the head core 1 as possible. Examples of photosensitive crystallized glass and ceramics containing lysium and silicon dioxide as main components include Zn ferrite and strontium titanate series.

There are the following methods for producing the magnetic head having the above-mentioned laminated structure.

As a first method, the material of the head core 1 is attached to the substrate 2 or 2'by a method such as sputtering, and the head is formed by glass adhesion.

As a second method, the substrates 2, 2'and the head core 1 are adhered using an organic adhesive, and the head is also formed using an organic adhesive.

A third method is a combination of the first and second methods.

Of these, the second method can be performed relatively easily, but the first method is superior in terms of the reliability of the gap method. However, since glass bonding is performed at a high temperature in the first method, when an amorphous alloy is used as the material of the head core 1, be careful not to reach the crystallization temperature of the amorphous alloy during glass bonding. There is a need.

When the surface of the tape sliding surface of the magnetic head thus formed was measured with a surface roughness meter in the direction perpendicular to the tape sliding direction, as shown in FIG. Quality alloy and sendust alloy are almost the same) is 200Å
It was found that the so-called uneven wear had occurred by falling to 400Å. This is caused when the front surface of the head is polished because the wear resistance of the magnetic head is emphasized and a substrate material having good wear resistance is used. The uneven wear always occurs in a laminated magnetic head made of different materials and cannot be avoided.

At the time of polishing the front surface of the head, as shown in FIG. 2 (c), it has a radius R when slightly enlarged in the thickness direction of the head chip. Regarding the shape of the head, the above-mentioned examination has been made, but the above-mentioned R has hardly been examined, and it is inevitable that the head is polished under the front surface polishing conditions (polishing tape, head protrusion amount, etc.). Has been decided,
Normally, R is finished to 2 mm or more.

Incidentally, R in the present invention is a value at the time of head front surface polishing, that is, at the initial stage of equipment attachment, and as shown in FIG. 2 (d), the broken line portion disappears due to wear and the R of the tip portion changes as the tape runs, It only refers to R at the time of head front polishing or equipment installation.

Therefore, VT is changed by variously changing R in the thickness direction of the head chip.
Fig. 4 shows the results of investigating the relationship between R and the head output by mounting the R device. Where R in the thickness direction of the head chip
Other than that, all heads have the same conditions. That is, crystallized glass containing silicon lysium and silicon dioxide as main components is adopted as the material of the substrate part, and amorphous alloy is adopted as the magnetic material part, and the track width is 30 μm and the core thickness is 130 μm.
And The substrate is shaved off and processed so that only the magnetic material portion becomes the tape sliding surface, and the output of 5 MHz of the head not affected by the substrate portion is shown as 0 (dB). The relative speed between the head and the tape was 3.75 m / sec, and a commercially available coated metal tape was used as the tape.

As is apparent from Fig. 4, it is the conventional chip finish.
Near 2mmR, it is about 3 (dB) lower. The relative output of the head improves when R is decreased compared to that, and 0.4m
It was found that it becomes almost 0 (dB) below mR and the spacing loss due to uneven wear can be almost ignored.

It is conceivable that if R is made small, the wear becomes large, but the relationship between the tape running time and the wear due to the difference in R is shown in FIG. According to the figure, when R is made small, the initial wear is large, but the wear after a certain period of time is the same as the conventional one, and it is understood that it is not a serious problem in practice.

Although it is considered that the output changes due to the change in R due to wear, as shown in FIG. 6, the head relative output with respect to the tape running time hardly changes, but rather increases. This increase is the effect of raising the gap depth due to head wear. The head relative output in FIG. 6 is shown with the same definition as in FIG.

In any case, it can be seen that by reducing R, the head output at the beginning of tape running can be easily obtained and the level can be maintained even after running for a long time. This is the initial R
However, even if the magnetic tape changes due to wear during running, it does not affect the head output, that is, the magnetic tape runs while conforming to R.

The reason for limiting the R in the thickness direction of the chip of the present invention to 0.2 to 1 mm is that the reduction in the head output is 3 in consideration of practicality.
This is because it is desirable to be within (dB).

On the other hand, if it is 0.2 mmR or less, the initial wear of the head is large, so that the range of 0.2 to 1 mmR is practically optimal.

The amorphous alloy in the examples may be formed by not only the ultra-quenched ribbon amorphous, but also by sputtering. The same applies to sendust alloys in bulk or ultra-quenched ribbon sendust.

Further, in the examples, the magnetic material has been described as having one layer, but it may have two or more layers if necessary.

(Effect of the Invention) According to the present invention, on the tape sliding surface of the magnetic head having the laminated structure, R is provided in the thickness direction of the head tip, and by setting this R to 0.2 to 1 mm, the apex of R, that is, the magnetic property. Since it comes into contact with the tape from near the material, head output can be obtained even in the initial stage of equipment installation, and there is no output drop even when the tape is run for a long time, which has the effect of prolonging practical life and improving performance.

[Brief description of drawings]

1 (a), (b) and (c) are perspective views of a conventional magnetic head, and FIG. 2 (a) is a plan view of a magnetic head having a general laminated structure for explaining the present invention. FIG. 3B is a side view, FIG. 2C is an enlarged view of the side view tip, FIG. 3D is an enlarged view of the side view tip while the tape is running, and FIG. 3 is a tape sliding surface of the magnetic head. 4 is a chart showing the data of the surface roughness meter, FIG. 4 is a chart showing the relationship between R in the thickness direction of the head chip on the front of the head and the relative output of the head, and FIG. 5 is the tape running time and head wear with respect to R. FIG. 6 is a chart showing the relationship of the amount, and FIG. 6 is a chart showing the relationship of the head relative output with respect to the tape running time with respect to R. 1 ... Head core, 2, 2 '... Substrate, 3 ... Winding window.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Toinchi Kenji Kadoma 1006 Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. In-company (56) References JP-A-52-56515 (JP, A) JP-A-55-91106 (JP, A)

Claims (2)

[Claims] 1. A head chip has a sandwich structure in which a magnetic material forming a head core is sandwiched between substrates from both sides,
The material of the substrate has higher wear resistance than the material of the magnetic material, and the radius of curvature R in the chip thickness direction on the tape sliding surface of the head chip that contacts the magnetic tape is 0.2 in the initial stage of equipment installation. A magnetic head characterized by being ~ 1 mm. 2. The magnetic head according to claim 1, wherein an amorphous alloy or a sendust alloy is used as a magnetic material forming the head core.