JPH0629769Y2 - Magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a magnetic head for a VTR (video tape recorder).

(B) Conventional technology A VTR called 8 mm video has high coercive force (14
The use of (00-1500 Oersted) metal tape has been proposed. This is because a recording medium capable of shortening the signal recording wavelength is required because it is necessary to increase the recording density in order to downsize the VTR.

On the other hand, as a magnetic head for this, a conventional ferrite head has a small saturation magnetization, so that a magnetic saturation phenomenon occurs and the performance of the metal tape cannot be fully utilized.
Therefore, the part near the operating gap where the magnetic saturation phenomenon is most likely to occur is formed of a magnetic material having a larger saturation magnetization than ferrite, such as permalloy, sendust, or amorphous,
A composite magnetic head in which the other portion is formed of ferrite has been proposed. Japanese Patent Laid-Open No. 58-175122 also targets such a magnetic head.

(C) Problems to be solved by the invention However, the composite magnetic head as described above has a problem that the S / N ratio is inferior to that of the sendust head or the amorphous head. 2 compared to sendust head, for example
~ 3 dB inferior. One of the causes is sliding noise peculiar to ferrite. It is believed that this is caused by the magnetostriction phenomenon when sliding on the tape, but its magnetostriction constant changes as a function of the ferrite composition, especially Fe
The larger the number of components, the larger (noise also increases).
However, in the above composite type magnetic head, Fe ₂ O ₃ was selected relatively large as 52 to 57 mol% of the total composition of the ferrite, so that sliding noise was large and the S / N ratio was poor.

(D) Means for solving the problem A metallic magnetic material having a saturation magnetic flux density higher than that of the core material is coupled to each of the operation gap forming surfaces of two ferrite cores that face each other through the operation gap. In the magnetic head, Fe ₂ O ₃ accounts for 45 to 50 mol% of Mn-Z.
A structure using an n-ferrite single crystal as the core material.

(E) Action Fe ₂ O ₃ is 50 mol% or less, which is smaller than that of the conventional one.
As a result, the magnetostriction constant becomes smaller and sliding noise is reduced.
Since 45 mol% is selected so as not to decrease, the saturation magnetization does not become extremely small and the recording performance does not deteriorate.

(F) Example In the figure, (1a) and (1b) are two ferrite cores that face each other through the working gap (2), and (3a)
(3d) is a sendust material arranged on the side of each operation gap forming surface of the ferrite core, (4) is glass arranged so as to define the track width, and (5) is a winding hole. Among the components of such a magnetic head, the ferrite core (1
a) In order to know the relationship between the composition ratio of the Mn-Zn ferrite single crystal used in (1b) and the S / N ratio of the magnetic head, ferrite samples of various composition ratios as shown in FIG. 4 were used.
The magnetic head shown in the figure was created and its S / N ratio was set to 1 kHz
It was measured in the frequency range of 4.2 MHz. Incidentally, in Samples A ... F of FIG. 4, the variation in composition is due to segregation during single crystal growth. The results of measuring the S / N ratio during reproduction of the magnetic heads prepared using these samples are shown in FIG.

As can be seen from FIGS. 4 and 5, when the Fe ₂ O ₃ component ratio is 53 mol% and 56 mol%, there is much noise and the S / N ratio is considerably poor. When Fe ₂ O ₃ content is 60 mol%, the noise is reduced, but the reproduction output is also reduced, so that the S / N ratio is somewhat improved. On the other hand, when Fe ₂ O ₃ is 50 mol% or less, the S / N ratio becomes good regardless of the amount of ZnO. However, the Fe ₂ O ₃ composition since the saturation magnetization is less than 45 mol% becomes the recording performance of the high coercivity tapes of metal tape is deteriorated less 45-50 mole%
Within the range, it is possible to realize a composite type magnetic head which has a good S / N ratio and does not impair recording performance.

In the above description, instead of the sendust materials (3a) and (3b), an amorphous material or other metallic magnetic material having a high saturation magnetic flux density may be used.

(F) Effect of the invention According to the invention, a composite type magnetic head having a good S / N can be realized, which is effective.

[Brief description of drawings]

The drawings are all related to the magnetic head of the present invention. FIG. 1 is a perspective view, FIG. 2 is a sectional view taken along line XX 'of FIG.
FIG. 3 is an enlarged view of a main part, and FIGS. 4 and 5 are views for explaining the configuration and effects. (1a) (1b) ... ferrite core, (2) ... operating gap, (3a) (3b) ... sendust material (metal magnetic material).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kozo Ishihara 2-18, Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (56) References JP-A-56-41519 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A magnetic head in which a metallic magnetic material having a saturation magnetic flux density higher than that of the core material is coupled to the respective operation gap forming surfaces of two ferrite cores which face each other through an operating gap. A magnetic head characterized in that the core material is Mn-Zn ferrite single crystal in which the proportion of Fe ₂ O ₃ is 45 to 50 mol%.