JPS59188817A - Magnetic head for vertical magnetic recording - Google Patents

Abstract

PURPOSE:To obtain a magnetic head for vertical magnetic recording having high recording efficiency by giving consideration to the ratio between the thickness of a main magnetic pole and the track width at a tip part of the magnetic pole as well as to the form at the periphery of said tip part. CONSTITUTION:The width of the tip part of a thin film made of a magnetic material of high permeability with thickness W, width T0 and length L is set at T within about 1/5L range. Then T/W<=15 or T0/T<=2 is satisfied for a main magnetic pole. Such a main magnetic pole, an energizing coil wound round the main magnetic pole and an auxiliary magnetic pole having the thickness and width which are larger at least than those of the main magnetic pole are provided to obtain a magnetic head for vertical magnetic recording. The tip form of the main magnetic pole is especially affected by the intensity of a vertical magnetic field. The width of the rear edge part is set larger than the tip part of a slip-shaped main magnetic pole 2 by narrowing down from both sides at the tip part, the steps are formed at the periphery of the tip part or narrowing down from a single side at the tip part. As a result, the magnetic flux is narrowed down less than a case where the same width is set from the tip part through the rear end part. Thus the recording efficiency is further improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a perpendicular magnetic recording head for efficient recording in a perpendicular magnetic recording system.

[Background of the invention]

A perpendicular magnetic recording device uses a magnetic tape that has an axis of easy magnetization in a direction perpendicular to the tape running direction, that is, in the thickness direction of the tape, and uses a perpendicular magnetic recording head that generates a strong magnetization distribution in this direction. is magnetized in a direction perpendicular to this, and the magnetization of the magnetic medium layer of the magnetic tape remains in this direction. In this way, when there is a residual magnetization distribution in the thickness direction of the magnetic tape, there is less generation of self-demagnetizing fields, and high-density recording with less loss is possible (see, for example, Japanese Patent Application Laid-Open No. 527134706).

Various types of perpendicular magnetic recording heads have been proposed for use in the above-described perpendicular magnetic recording devices. For example, as shown in FIG. 1, a recording medium 1 is sandwiched between a main magnetic pole 2 made of a high magnetic permeability material such as a permalloy thin film, and a rectangular plate-shaped auxiliary magnetic pole 3 made of ferrite or the like around which an excitation coil 4 is wound. When these are opposed to each other, the magnetic field of the auxiliary magnetic pole 3 is concentrated on the tip of the main magnetic pole 2, so that the tip of the main magnetic pole 2 is easily magnetized and good recording efficiency can be obtained. However, if the recording medium l is disk-shaped, or if the
There is a drawback that this method is difficult to apply as is when the magnetic head is rotated as in R.

In contrast, as shown in FIG. 2, a main magnetic pole 2 made of permalloy or the like and an auxiliary magnetic pole 3 around which an excitation coil 4 is wound are made in a U-shape, and both cover the surface of the recording medium 10, that is, the magnetic medium layer. A type that is installed on the side has been proposed. however,
In this case, a plate-shaped body 5 made of a high magnetic permeability material is arranged on the back surface of the recording medium 1 so as to face the main magnetic pole 1 and the auxiliary magnetic pole 3, but the high magnetic permeability material layer is integrated with the recording medium 1. It is necessary to set it up.

Conventionally, in the perpendicular magnetic recording head as described above, when an excitation coil is wound around the main magnetic pole 2 side, the magnetic flux from the main magnetic pole 2 is not efficiently concentrated on the magnetic medium layer of the recording medium l, resulting in a decrease in recording efficiency. The disadvantage of poor performance has long been a problem.

To explain the above points specifically, in the past, great attention was not paid to the dimensional ratio T/W between the thickness W) and the track width (T) of the main magnetic pole 2, so it was This is something that magnetic heads could not achieve. That is, the reason for this is that the main magnetic pole 2 (thickness W) is wound with the excitation coil 4 as shown in FIG.

In order to perform recording using a track width T) of 1 μm or less, the thickness W of the main magnetic pole 2 must be set to 1 μm or less. However, assuming a home VTR, the track width T is at least 30 μm2 and usually 60 μm.
Considering audio use, approximately 500 μm is required. In this way, when the track width of the main magnetic pole 2 becomes large relative to its thickness, even if the main magnetic pole 2 is magnetized in its axial direction by the excitation coil 4, the magnetic pole This is thought to be because the magnetization is bent in the track width direction at the tip, making it impossible to effectively obtain a magnetic field in the perpendicular direction, resulting in a decrease in recording efficiency.

[First aspect of the invention] Objective and summary of the present invention In order to solve the problems of the prior art, the first aspect of the present invention is to improve the dimensional ratio between the thickness W of the main pole and the track width T at the tip and the width of the track width near the tip. An object of the present invention is to provide a magnetic head for perpendicular magnetic recording with good recording efficiency by taking the shape into consideration.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

Figure 4 shows the unit track when the ratio T/W is changed, where the thickness W and track width T of the main magnetic pole 2 made of a strip-shaped permalloy thin film are as shown in Figure 3. It is a figure which shows the result of experiment regarding the change rate of the strength of the perpendicular magnetic field per width.

As can be seen from the figure, the decrease in the strength of the vertical magnetic field is %
If it is allowed up to %, T/W<4, and if it is allowed up to %, T/W<15.

The value of W should be chosen.

On the other hand, it is the shape of the tip of the main pole that particularly affects the strength of the vertical magnetic field. Specifically, it has been experimentally confirmed that, where the length of the magnetic pole is L, the vicinity of the tip in the range of approximately 'AL or less has a particularly large effect. Therefore, the fifth
As shown in Figure (aL) (b) and (C), the tip of the strip-shaped main magnetic pole 2 should be narrowed from both sides, the vicinity of the tip should be shaped like a step, or the tip should be narrowed from one side. If the rear end is made wider than the tip by constricting it, the magnetic flux will be constricted more than if the rear end is the same width as the tip, further improving efficiency.Main magnetic pole If the width of the rear end of 2 is T, and the width of the tip is T, then T
, /T≦2, the efficiency increases to a value close to 2, and a strong vertical magnetic field can be obtained with the same excitation current value. However, To
Even when /T was set to 2 or more, the improvement was the same as when it was set to about 2.

As explained above, with respect to the length L of the main pole, the track width '1' and the thickness W at one end of the range less than or equal to the length L
If the value of is set so that T/W≦15, and the width To on the rear end side of the magnetic pole is set so that T/To≦2, a magnetic head for perpendicular magnetic recording with high recording efficiency can be obtained. is obtained.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of a conventional magnetic head for perpendicular magnetic recording, Figure 3 is a diagram showing the magnetization distribution near the tip of the main pole when an excitation coil is wound around the main pole, and Figure 4 is an illustration of a conventional magnetic head for perpendicular magnetic recording. , a curve diagram showing the change in the strength of the perpendicular magnetic field per unit track width when changing T/W in a main pole made of a rectangular permalloy thin film where the thickness of the main pole is w and the track width is T. , Figures 5(a) and (b). fc) is a perspective view showing an embodiment of the main magnetic pole of the present invention. In the figure: 2: Main magnetic pole 3: Auxiliary magnetic pole 11: Exciting coil Patent attorney Junnosuke Nakamura 1 Figure left 2 Figure left 3 Figure 74 Figure 5i - Ahead 5 [¥] Continued from page 1 0 Inventor Uesaka Hideo Fujiwara, Hideo Fujiwara, 280 Higashi-Koigakubo-chome, Kokubunji City, Hitachi, Ltd.Central Research Laboratory, Hitachi, Ltd.

Claims (1)

[Claims] 1. A thin film of high magnetic permeability magnetic material having a length of thickness W1 and width To is narrowed to a range of about %L on one tip side of the thin film, and the width of the tip (track width) is T( T < To ), and the above W, To, T, and L are T/W <15 and To
/T (having a main magnetic pole that satisfies the following two conditions, an excitation coil wound around the main magnetic pole, and an auxiliary magnetic pole having a thickness and width that are at least larger than the thickness and track width of the main magnetic pole. A magnetic head for perpendicular magnetic recording featuring: