JPS61292214A - Magnetic head - Google Patents

Abstract

PURPOSE:To obtain a magnetic head with excellent reliability, durability and workability and coping with a high coersive force magnetic medium by designing the saturated magnetic flux density of a magnetic film so as to be larger gradually from a face in contact with a core main body toward a head gap. CONSTITUTION:The saturated magnetic flux density of a part of the magnetic film 12 in contact with a ferrite-made core main body 11 is comparatively small as 4,000-5,500 the same as that of ferrite and designed to be larger in the broadwise direction of the film, that is, toward a head gap 13 gradually and the gap 13 is formed by SiO2. Thus, the characteristic with excellent reliability, durability and workability is provided and no undesired signal other than a desired signal is recorded and the head copes with a high coersive force recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic head used in a magnetic recording device for recording and reproducing information.

Conventional technology Recently, with the development of information society, images and sounds have become increasingly important.

There is a desire for devices that can record and reproduce information such as text and numbers at higher density, and the development of magnetic recording is particularly remarkable.

In magnetic recording, in order to achieve high-density recording, the recording medium has a high saturation magnetic flux density (Bs) and a high coercive force (Hc).
Recording materials with large sizes have come into use.

On the other hand, ferrite is widely used in magnetic heads, but since it has a low saturation magnetic flux density, writing has become difficult as recording media have become higher in BS and higher in HO. Therefore, metallic sendust and amorphous materials with large BS are being considered as core materials for magnetic heads in place of ferrite. However, magnetic heads using metal cores are less reliable than magnetic heads with ferrite cores.
It is inferior in terms of durability and workability. Therefore, ferrite, which has a proven track record in the past, is used as it is as the core material, and only the gap part of the head core that is most likely to be magnetically saturated is laminated with a metallic magnetic film with a high saturation magnetic flux density.
IG head (Metal ingzp head)
Development is progressing (Reference).

IEEE Transactions on Magnetics, XEEE Trans6Mag
n.

MAG-18, 1146, 1982).

Problems to be Solved by the Invention However, in the above-mentioned MIG head, in addition to the original gap of the head, a pseudo gap is formed at the boundary between the ferrite and the metal-based magnetic film, causing unnecessary distortion in the reproduction output waveform. There is a problem.

Therefore, the present invention is intended to solve the above problems, and is not only superior in terms of reliability, durability, and workability, but also capable of preventing unnecessary waveform distortion from occurring in the output waveform. It is an object of the present invention to provide a magnetic head that can be used with high coercive force magnetic media.

Means for solving the problems and the technical means of the present invention for solving the above problems are that a magnetic film is provided on at least one side of the core body made of ferrite on the head gap side, and this magnetic film is saturated. The magnetic flux density is configured to gradually increase from the surface in contact with the core body toward the head gap side.

Function: With the above configuration, the present invention can prevent a sudden change in the magnetic field from occurring at the boundary between the core body and the magnetic film, thereby preventing unnecessary distortion from occurring in the reproduced output waveform.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 1, 1o is a core of a magnetic head, and a magnetic film 12 is provided on at least one surface of a core body 11 made of ferrite on the head gap 13 side. 14
is molded glass to reinforce the head chip, 15
is a recording/reproducing coil.

The core body 11 made of ferrite has a saturation magnetic flux density of 4000
~5500 Gauss. The saturation magnetic flux density of the magnetic film 12 at the portion in contact with the ferrite core body 11 is relatively small at 4ooO to 5500, similar to ferrite, and gradually increases in the thickness direction of the film, that is, as it approaches the head gap 13 side. It is set. The gap 13 is formed of SiO2.

Next, a trial production row of the magnetic film 12 in this practical row will be explained. FIG. 2 schematically shows a prototype series when forming the magnetic film 12 using the vacuum evaporation method.
16 is a chamber, 11 is a ferrite core body, 1
7 is a material with a small saturation magnetic flux density, and 18 is a material with a large saturation magnetic flux density. 19 is a shutter for controlling the amount of evaporation of materials 17 and 1.8;
The composition is controlled by the amount of opening and closing, and the saturation magnetic flux density of the magnetic film 12 is controlled as described above. It was also possible to perform similar control by adjusting the input power, which determines the evaporation rate.

FIG. 3 shows a prototype array for forming the magnetic film 12 using the sputtering method. In the figure, 20 is a chamber, 11 is a core body made of ferrite, 21 is a target with a small saturation magnetic flux density, and 22 is a saturation magnetic flux. The high-density target 23 is a shutter for controlling the amount of sputtering. By controlling the amount of opening and closing of the shutter 23, the saturation magnetic flux density of the laminated magnetic film 12 can be gradually increased as described above.

Similar control can also be achieved by adjusting the input power. In addition, the evaporation source 17.1 mentioned above
8 and the targets 21 and 22 and the core body 11 can be sufficiently spaced to prevent compositional unevenness. The saturation magnetic flux density of the magnetic film 12 can also be controlled by moving or rotating the laminated core body 11 of ferrite fissures within the vacuum chamber 16.

Alternatively, a method may be used in which a single target is used, the bias magnetic field is controlled, and magnetic films 12 having different compositions are laminated. In short, in this embodiment, the saturation magnetic flux density of the laminated magnetic film 12 is almost the same on the head core body 11 side, and gradually increases as the film thickness increases, that is, as it approaches the head gap 13 side. If so, any film forming method may be used.

The relationship between the thickness of the metal magnetic film 12 obtained as described above and the saturation magnetic flux density is shown in FIG. 4(a). When the film thickness is thin, the saturation magnetic flux density is almost the same as the core material of the head, and as the film thickness increases, it gradually increases, and after that, the film composition has the maximum saturation magnetic flux density. Here, as a method of gradually increasing the saturation magnetic flux density, it may be increased continuously as described above, or the saturation magnetic flux density may be gradually increased in a stepwise manner as shown in FIG. 4(b). .

Next, the operation of the above embodiment will be explained with reference to FIG.

FIG. 6 shows an enlarged view of the vicinity of the magnetic head gap. Ferrite, which has a relatively low saturation magnetic flux density, is used as the core body 11 of the magnetic head, and a metal-based magnetic film 12, which has a higher saturation magnetic flux density than the ferrite, is laminated on the head gap 13 side as described above (in the figure, the magnetic head gap 13
This figure shows a case where magnetic films 12 are provided on both sides of the magnetic film 12. ).

In the case of a conventional array in which the saturation magnetic flux density is uniform within the magnetic film 12, the horizontal magnetic field distribution on the head surface when a sufficient write current is passed is as shown in FIG. 5(b). The magnetic field strength is strongest at the end of the head gap 13 and decreases as the distance from the gap 13 increases. However, since magnetic saturation occurs at the boundary between the metallic magnetic film 12 and the ferrite core body 11, a convex portion 24 as shown in the figure appears on the magnetic field strength distribution curve. This convex magnetic field distribution causes unnecessary signals to be recorded on the recording medium. This is what is called a pseudo gap.

In the case of this embodiment in which the saturation magnetic flux density is gradually increased in the thickness direction within the magnetic film 12 as described above, the horizontal magnetic field distribution when a sufficient write current is passed is as shown in FIG. 5(C). become. In this case, since the metal-based magnetic film 12 and the ferrite core body 11 are joined together with a smooth saturation magnetic flux density, a clear convex magnetic field distribution unlike the conventional row does not occur. Therefore, unnecessary signals are not recorded as in the conventional column.

Effects of the Invention As is clear from the above description, according to the present invention, a magnetic film is provided on at least one surface of the core body on the head gap side, and the saturation magnetic flux density of this magnetic film is changed from the surface in contact with the core body to the head gap side. Reliability because it is configured to gradually increase in size.

It has excellent properties such as durability and workability, and also prevents unnecessary signals from being recorded in addition to the original signal, making it compatible with high coercive force magnetic recording media.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the magnetic head of the present invention;
Fig. 2 is a schematic explanatory diagram showing one example of a method for forming a magnetic film, Fig. 3 is a schematic explanatory diagram showing another example of a method for forming a magnetic film, and Figs. A diagram showing the relationship between film thickness and saturation magnetic flux density, Figure 6 (&) is an enlarged view of the vicinity of the magnetic head gap, Figure 6 (b) is a horizontal component magnetic field distribution diagram of the conventional example, and Figure 5 (C) is an enlarged view of the vicinity of the magnetic head gap. It is a horizontal component magnetic field distribution diagram of a present Example. 10... Core, 11... Core body, 1
2...Magnetic film, 13...Head cap, 14...Mold glass, 16...
·coil. Name of agent: Patent attorney Toshio Nakao and one other person
Gore ff --- Core failure 14 -- Mold method/Last f5 -- Goul f9 --- Shi 7g 22 -- High foam 1.・4th A Mansara no Tsukasa

Claims (1)

[Claims] A magnetic film is provided on at least one side of the ferrite core body on the head gap side, and the magnetic film is configured such that the saturation magnetic flux density gradually increases from the surface in contact with the core body toward the head gap side. magnetic head.