JPH0760488B2 - Magnetic head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head used in a magnetic recording device that records and reproduces information.

2. Description of the Related Art Recently, a device for recording and reproducing information such as images, sounds, sentences, and numerical values with higher density has been desired with the development of information society, and the development of magnetic recording is remarkable.

In the magnetic recording, to achieve high density recording, the recording medium saturation magnetic flux density (B _S) is high, has come to Okiki recording material The coercive force (Hc) can be is used.

On the other hand, although ferrite is widely used in magnetic heads, it has a low saturation magnetic flux density, which makes it
B _S of, writing with an increase in Hc of it has become difficult. Therefore, as the core material of the magnetic head, metal-based sendust or amorphous having a large B _S is being considered in place of ferrite. However, a magnetic head using a metal-based core is inferior in reliability, durability, and workability to a magnetic head having a ferrite core. Therefore, the so-called MIG head (Metal in gap head) in which ferrite, which has a proven record in the past, is used as it is as the core material, and only the gap part where magnetic saturation is most likely to occur in the head core is laminated with a metal-based magnetic film having a high saturation magnetic flux density Is being developed (reference, IEE Transactions on Magnetics, IEEE Trans.Magn., MAG-18, 1146.198).
2).

Problems to be Solved by the Invention However, in the above MIG head, a pseudo gap other than the original gap of the head is formed in the boundary portion between the ferrite and the metal-based magnetic film, and unnecessary distortion occurs in the reproduction output waveform. There is a problem that ends up.

Therefore, the present invention solves the above-mentioned problems, and is not only excellent in reliability, durability, and processability, but also prevents 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 made compatible with a high coercive force magnetic medium.

Means for Solving the Problems And, in order to solve the above problems, the present invention provides a core body made of ferrite having a head gap, and a single core provided on at least one of the end surface on the head gap side of the core body. Of the magnetic film, the saturation magnetic flux densities of the core body and the magnetic film are substantially equal at a boundary portion between the core body and the magnetic film, and the magnetic flux is directed from the boundary portion toward the head gap side. The magnetic film is configured such that the saturation magnetic flux density of the magnetic film gradually increases.

Effect With the above configuration, the present invention can prevent an unnecessary distortion in the reproduction output waveform by preventing abrupt magnetic field change at the boundary between the core body and the magnetic film.

Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 10 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. Reference numeral 14 is a mold glass for reinforcing the head chip, and 15 is a recording / reproducing coil.

The core body 11 made of ferrite has a saturation magnetic flux density of 4000 to 5500.
Gauss. The magnetic film 12 has a saturation magnetic flux density of 4000 to 400, which is the same as that of ferrite, in the portion in contact with the ferrite core body 11.
It is set to a relatively small value of 5500, and gradually increases along the thickness direction of the film, that is, toward the head gap 13 side. The gap 13 is made of SiO ₂ .

Next, a trial manufacture example of the magnetic film 12 in the present embodiment will be described. FIG. 2 schematically shows a prototype example of forming the magnetic film 12 by the vacuum deposition method. In the figure, 16 is a chamber, 11 is a ferrite core body, and 17 is a small saturation magnetic flux density. Material 18 is a material having a high saturation magnetic flux density. Reference numeral 19 denotes a shutter for controlling the vapor deposition amount of the materials 17 and 18, and the composition is controlled by the opening / closing amount of the shutter 19, and the saturation magnetic flux density of the magnetic film 12 is controlled as described above. It was also possible to perform the same control by adjusting the input power that determines the evaporation rate.

FIG. 3 shows an example of a prototype in which the magnetic film 12 is formed by the sputtering method. In FIG.
Is a ferrite core body, 21 is a target with low saturation magnetic flux density, 22 is a target with high saturation magnetic flux density, 23
Is a shutter for controlling the amount of spatter. By controlling the opening / closing amount of the shutter 23, the saturation magnetic flux density of the laminated magnetic films 12 can be gradually increased as described above. The same control can be performed by adjusting the input power.
It should be noted that compositional unevenness can be prevented by providing a sufficient distance between the vapor deposition sources 17 and 18 and the tardats 21 and 22 and the core body 11 described above. The saturation magnetic flux density of the magnetic film 12 can also be controlled by moving or rotating the laminated ferrite core body 11 in the vacuum chamber 16. Alternatively, a method of controlling the bias magnetic field using one kind of target and laminating the magnetic films 12 having different compositions may be used. In short, in the present embodiment, the saturation magnetic flux density of the magnetic film 12 to be laminated is almost the same on the head core body 11 side, and as the film thickness increases, that is, the head gap 13 side is gradually increased. If there is any, the film forming method may be any method.

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

Next, the operation of the above embodiment will be described with reference to FIG. FIG. 5 shows an enlarged view of the vicinity of the magnetic head gap portion. Ferrite having a relatively small saturation magnetic flux density is used as the core body 11 of the magnetic head, and the metal-based magnetic film 12 having a larger saturation magnetic flux density than the ferrite is laminated on the head gap 13 side as shown above (in the figure, the head is shown). Magnetic film on both sides of the gap 13
The case where 12 is provided is shown. ).

In the case of the conventional example in which the saturation magnetic flux density is uniform in the magnetic film 12,
The horizontal magnetic field distribution on the head surface when a sufficient write current is flown 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 core body 11 made of ferrite, a convex portion 24 as shown in the figure appears in the distribution curve of the magnetic field strength. Due to this convex magnetic field distribution, an unnecessary signal is 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 of the magnetic film 12 as described above, the horizontal magnetic field distribution when the write current is sufficiently flown is as shown in FIG. 5 (c). become. In this case, since the saturation magnetic flux density is smoothly joined to the metallic magnetic film 12 and the ferrite core body 11, a sharp convex magnetic field distribution unlike the conventional example does not occur. Therefore, an unnecessary signal unlike the conventional example is not recorded.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, a single 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 the magnetic film is determined by the core body and the magnetic film. Are made substantially equal to each other at the boundary portion, and gradually increase from the boundary portion toward the head gap side, so that they have excellent characteristics such as reliable manufacturing, durability, and workability, and are unnecessary for other than the original signal. It is possible to support a high coercive force magnetic recording medium without recording various signals.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a magnetic head of the present invention,
FIG. 2 is a schematic explanatory view showing an example of a method of forming a magnetic film, FIG. 3 is a schematic explanatory view showing another example of a method of forming a magnetic film, and FIGS. 4 (a) and 4 (b) are magnetic film forming methods. FIG. 5 (a) is an enlarged view of the vicinity of the magnetic head gap, FIG. 5 (b) is a horizontal component magnetic field distribution map of the conventional example,
FIG. 5 (c) is a horizontal component magnetic field distribution diagram of this embodiment. 10 …… Core, 11 …… Core body, 12 …… Magnetic film, 13 …… Head gap, 14 …… Mold glass, 15 …… Coil.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuhiko Nakayama 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Matsushita Giken Co., Ltd. (56) Reference JP-A-55-160322 (JP, A) Kai 57-32370 (JP, A) JP 58-64619 (JP, A) JP 60-202502 (JP, A) JP 60-234209 (JP, A) Actual 60-123709 (JP) JP, U)

Claims (1)

[Claims] 1. A magnetic head having a ferrite core body having a head gap and a single magnetic film provided on at least one of the end surfaces of the core body on the head gap side, the core body comprising: At the boundary with the magnetic film, the saturation magnetic flux densities of the core body and the magnetic film are substantially equal to each other, and the saturation magnetic flux density of the magnetic film gradually increases from the boundary toward the head gap side. A magnetic head comprising a film.